Heating News – Spring 2017

Grid parity – are we there yet?

Photvoltaic panels might not be particularly efficient but they are certainly simple and cheap to run. Stick ‘em in the sun and they make electricity with no further ado. This is why over the next five years large scale PV solar for the grid will be level pegging with the existing power generation costs. So this is grid parity. As power costs rise and panels get cheaper and better, the post parity world should see PV power starting to put the brakes on energy price rises. Of course PV power won’t dominate, there just won’t be enough of it to do so, but the underlying principle will be self evident and compulsive enough to set the stalled PV train in motion again.

There is another reason to give PV renewables a boost. The nascent electric car era is going to tax the grid beyond current capacity. While petrol stations stand empty the grid will be flat out, trying to keep up. A world where the car in your garage costs virtually nothing to run is getting tantalisingly close but the Government clearly needs to act now and raise incentives for domestic PV installations.

Right now though, on the domestic front, parity is more complicated despite panel prices having fallen to around £1,000 per kWp plus the installers cost.

Take a typical 3 bed UK house with annual electricity bills of £450. A 4kWp array costing £6,500 will make a derisory £320 a year in savings and FIT income. Payback over 20 years just says ‘no way thanks,’ so no immediate evidence of parity being anywhere near.  However, before we give up, lets take another approach and scale up enough to run a small heat pump; enough to knock out half (no sun at night) the £650 annual gas bills and make the other half at about the same cost as gas would have been. A 6kWp array making around £450 a year and costing £8,500 to install plus another £5,000 for the heat pump makes a total cost of £13,500 for an effective return of £875.

That 6.5% return looks a bit more interesting! What if we took advantage of these crazy low borrowing rates and borrowed the £13,500 from, say, Sainsburys for an annual payment of  £2,267over 7 years? We can expect a little help from the Renewable Heat Incentive payments for 7 years applied to the air source heat pump – like £770 a year according to the Ofgen example.

Deducting the £875 savings and the RHI £770 you effectively pay £622 for seven years until the loan is all paid off. You are then left with £875 a year in benefits (and rising) for as long as the kit lasts, which should be a good 13 years. This looks like a sensible way to prepare for a comfortable retirement; almost like a pension. Put an electric car in the garage and another major cost will be eliminated.

Very attractive RHI incentives are also available for solar thermal panels (although making DHW only). £220 a year in the Ofgen example. Even more noteworthy is the emphasis on the more expensive ground source heat pumps where the example returns jump up to £2,100 a year for 7 years. They not only pay a much higher tariff (19.64p/kW vs. 7.63) but the higher COP of the GSHP affects the calculations in your favour. The calculations are based on your energy demand taken from your EPC certificate and you can easily do them yourself.

My definition of grid parity is when it pays to borrow money to buy solar PV. On that basis I’d say we are still some way off but the RHI incentives are making combined systems worth considering.

You can see these and other ideas explored more on an eco-house design here. This house is designed to be virtually off grid and able to provide a separate living unit for grannies or Airbnb paying guests.

To delve deeper into eco-energy concepts you might like to look on Amazon where you can download, for Kindle, my book ‘Dream House – Down to the details’ £2.45. Details

 

For the Italian readers – low borrowing rates – time for a heating makeover.

There is no getting away from the fact that the cost of heating in Italy is a major issue. The wood/solar solution is usually the answer but the high installation cost often leaves householders trapped in an expensive rut. OK, so lets go back to Sainsburys to borrow £8,500 for a perfect solar/wood stove/heatbank solution to be delivered to your door. £152 a month (£1,824 a year) for 5 years gives you a delightful system that will run for around €1,200 a year. This is deluxe kit. The best stove, the best heat bank and a huge 3 panel solar array.  You’ll be warm as toast and there will be masses of hot water. The heating even works in a power cut so you will be safe and even able to cook if disaster strikes. Sorry to keep flipping currencies, but this means that if your heating bills exceed £3,000 a year then it’s time to have a think about a makeover. So many owners of Italian houses spend double this but there is no need to be one of them. If you need a hand to figure out if a makeover would work for you, just get in touch on the contact form below.

A plug for Italian eco-heating.

Heating in Italy

Word is getting round about eco-heating in Italy. See The Daily Telegraph article here.

In praise of the Casio solar watch.

This story started at the clock museum in Greenwich. I was admiring John Harrison’s (he of the Longitude prize) sea going clock, with all the elaborate pendulums and springs, and realised that his strange machine was more accurate, even at sea, than my £1,000 Breitling Aerospace titanium watch. Now I loved that watch but this was too much to bear so it was sold straight away to someone in the office and five of us there did a deal to get some Casio Waveceptor Toughsolar watches at £130 each.

These watches tune in to the atomic clock at Rugby each night so they are absolutely accurate. The expression ‘What do you make the time?’ is redundant, the time is what it is, period. The first pip goes exactly when the second hand hits the top, even when the clocks change twice a year the hands wind an hour on or off during the night. There is no knob on the right to adjust the time (obviously) and this facilitates the sport of asking owners of expensive watches why they have a knob on their watches. ‘To adjust the time – really?’

The face of the watch hides a solar panel and the metal strap lasts without wear so there are no tedious battery and strap replacements (£30 and £70 respectively on the Breitling).

All this was 10 years ago and the watch, being waterproof, has almost never been off my wrist. It just ticks away faithfully and relentlessly, over 315 million ticks so far, a number of tiny mechanical jolts that beggars belief.

So after the first ten year stint old watch, I salute you.

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Eco-heating system for heat pumps

Ultimate Eco-heating system

Ultimate Eco-heating system

Ecological heating (Eco-heating)

The Eco-heating goal is simple.  To use free or green energy (solar/wood) so effectively that expensive fossil fuels, energy bills and the carbon footprint disappear.  The only reason to be attached to the grid is to supply it; well not quite, we might need the grid to smooth any fluctuations but we certainly don’t need much of it.

Modern houses are well insulated and need a lot less energy to run than before and a few technological advances have made Eco-heating absolutely viable.

As a starting point, a tank of water – a heat store – is required to integrate various heat sources and demands. A single heat store makes an excellent heating system but two tanks are altogether much better, especially when it comes to integrating solar and a heat pump. So much more is easily optimised with twin tanks that this is the future for eco- heating systems.

Before you start to plan your own ultimate heating system there are a few points to consider:-

Photovoltaic panels (PV) rarely produce their rated output.

On a bad day they produce only around a third of their rated output – say 50W per square metre.

Background electrical demand (fridge, computers, lights, TV etc.) can often be as high as 1kW

The PV panel array will have to be much bigger than the usual 4kWp (16 panels) for there to be enough surplus power to make an eco-house.

 A heat pump takes electrical power and delivers around 3 times as much more energy in the form of hot water. This engineering miracle might be the core of the system, but …

The power multiplier

The power multiplier

…. the times 3 trick (coefficient of performance or COP) is highly variable, and depending on outside temperatures and delivery temperatures, can vary from 2 to 5. The manufacturer’s quoted COP is for very specific conditions which you might not see very often.  Even the quoted power output of a heat pump will not be reached when it is very cold outside.

 

Air source heat pumps are a better choice than ground source heat pumps

They cost less and are easier to install. For the full argument see:-

https://originaltwist.com/2015/02/27/air-source-heat-pumps-and-the-renewable-heat-incentive/

https://originaltwist.com/2014/03/19/heat-pumps-in-southern-europe-air-or-ground/

PV + heat pump = Free heating

A heat pump on a COP of 3 redresses the shortcomings of the PV panels on that bad day, so a PV panel and heat pump combination can deliver 150W per square metre of panel and two or three times as much on good days.  This energy, in the form of hot water, can be delivered to underfloor heating which usually uses about 50W per square metre of floor and never more than 100W (which would make your feet hot).  So, for a rule of thumb, the PV panel area should be about half the heated floor area, plus up to another 20 square metres to cover background consumption.  Therefore, most self-supporting Eco-houses are likely to have up to 40 PV panels on the roof; a lot.

Air source heat pumps run much more efficiently during the day when the air is warmer.

Not only more efficiently but combined with PV panels much of the daytime energy produced is free.  Obviously big PV and a slightly oversized heat pump can produce excess energy which could keep the heating on after the sun goes down. The surplus energy will need to be stored in tanks of water – big ones.

A house with high thermal mass will also work better in this respect.

Solar thermal panels are much cheaper and much more efficient than PV.

OK, they don’t make electricity nor do they print money like PV can.  However, given some sun, they do produce very hot and free high grade water heating, so the system should have an excess of them.  Massive solar is hard to manage and here again big tanks are part of the answer.

Solar thermal panels can be made to run more efficiently.

Solar panels can only heat a tank that is cooler than they are. In winter when the tank is usually already hot and solar is weak the panels often stop working altogether.  Given 2 tanks however – one hot and one cool – the panels will run almost daily throughout the year and this dramatically improves effective panel efficiency. The Original Twist solar stripper circuit decides which tank, or both together, can use the available heat more favourably.

A pair of 500 litre tanks are only 2m high and together under 1.5m wide.  Tanks up to 500 litres can be made of light gauge steel so they are relatively cheap and easy to handle.

Gas boilers – not quite redundant

On the coldest night the heat pump with reduced power output and the lowest COP might be struggling, especially if it was sized within the limitations of single phase electricity. A gas boiler is a towering powerhouse by comparison, producing instant high grade heat at a low price. Hot water recovery times are just minutes and a shower could run hot forever if required.  For a larger eco-house, a gas boiler for very occasional use makes sense and ensures that there are no compromises to comfort whatsoever.

Under floor heating is not always best.

Bedrooms need to be heated quickly, often briefly, and preferably not with a hot floor under the bed.  Floors of upstairs bedrooms are often reasonably warm already because they are above rooms which are heated all day so paying to heat them more makes little sense.  The answer for bedrooms is the fan-coil unit which is essentially a hot water powered fan heater. Not only will they heat the room in minutes, but connected to a suitable heat pump they will cool it as well.  Air quality can be enhanced by UV purification, a boon to asthma and hay fever sufferers.

Towel rails are different.

After your shower the towel rails will need to be on long after you have got up or gone to bed. The timing and heating requirements for towel rails is completely at odds with the rest of the system and they need to be properly integrated with a dedicated supply.

Wood burning stove

Mankind has been sitting round fires for thousands of years; for many people it is unthinkable not to have a real fire in the home.  We are talking eco-heating here so an open fire is out of the question but a good stove is much nicer to live with anyway.  A big stove with a big view of the flames will be too hot for most rooms so it will need to be connected to the water tanks in order to take some heat away. That’s no bad thing as high grade hot water is not so readily produced by the heat pump. A well matched stove can usually cope with all the hot water and heating needs which relegates the heat pump to an auxiliary role and certainly means that smaller heat pumps can be considered.

Controls

Although it is not an absolute requirement, the eco-heating system will work much better with a home automation system such as the Z-Wave Vera. The hot water circulation system, for example, can be activated by sensors in the bathrooms when they turn on the lights. Temperature sensors and relays to activate pumps and valves can be found in the Qubino Z-Wave flush relay which has a built in temperature sensor.  The destratification routine (see below) can be triggered by the integrated temperature sensor and the short pump runs monitored by a controller which easily copes with ‘if this then that’ situations.

Efficiency – the humbug

Just a reminder; the sun is free. There is no need to agonise over panel efficiency. The most reliable flat plate thermal panels are cheap so if you need more power just add more. Anyway, during the hotter months they are more efficient than evacuated tube types.

To store daytime heat pump production, the target temperature needs to be raised and that is relatively inefficient compared with driving the under-floor heating directly. Again the pump is usually running free, courtesy of the sun, so the efficiency doesn’t matter.

 

The Eco-heating system

Considering all of the above your ultimate Eco-heating system should be like this:-

Much of the suitable roof surfaces will be covered in PV and thermal solar panels.

An air source heat pump

Air conditioning via the heat pump

Under floor heating on the ground level

Fan-coils in bedrooms

Fan-coils in some living rooms for air conditioning

A gas boiler (optional)

A twin tank heat store system. Up to 500 litres x2.

A wood burning stove connected to the tanks

A system that can optimally integrate all of the above with no compromises at all is a tall order.  Here it is though; the Original Twist Eco-heating System.

Two tanks it is then – one hot one cooler – but with some sound thinking around the connections to the heat sources:-

Domestic hot water delivery.       

Fresh and pressurised water is heated by the hot tank via a plate heat exchanger – standard heat store practice. However, as the hot tank water will be rather modestly heated by a heat pump, the ability of the plate heat exchanger to cope with icy fresh water can be compromised. So to warm the incoming water it first runs through an internal coil in the cooler tank before getting to the external heat exchanger on the hot tank. The pre-warming is not mission critical so there are no controls or pumps to worry about. It’s just a passive coil in the cooler tank.

Back on the hot tank the usual temperature limiting valve – anti scalding – has been dropped in favour of electronic regulation of the heat exchanger flow pump with a Steca  TF A603 MC+ controller. This slows down the pump to give a precise output temperature and so leaves more water at the top of the tank ready for more showers. The flow out of the heat exchanger and to the bottom of the tank is also cooler which aids cooling of the solar coil.

Water circulation around the house is essential to save water wastage and eliminate that annoying wait for hot water.  The same Steca controller also regulates the circulation pump speed.

Preheating the domestic hot water via the cool tank not only makes a heat pump a feasible hot water maker but it also raises the efficiency in a subtle way. The water in the cool tank is heated just enough to supply the floors and fan-coil units and a heat pump does that very efficiently. Blending this cheaper energy into the hot tank system gives an efficiency boost and also allows the hot tank to be maintained a little cooler which gives another efficiency boost.

Other potential heat inputs to the hot tank (wood, solar and gas) are not disruptive to stratification so hot water drawn from the top is always ready for service.

The solar stripper circuit.

Solar thermal panels connected to a hot tank which is already hot – as it would be with a stove or heat pump keeping it ready for hot water delivery – will be effectively switched off in weak sunlight.  But given access to a cool tank they will leap into action at the first glimmer of sunshine, practically every day of the year. Low temperature solar flow addresses the coil in the cool tank first but as soon as it is hot enough it is switched to the hot tank. The flow emerging from the hot tank is usually still very hot so the return flow to the panels goes back via the coil in the cool tank to strip out some more energy.  The panels not only run throughout the year but more efficiently due to a cooler return feed.

The Original Twist Solar Stripper Circuit achieves all this with a special 3 port Coster valve that does not interrupt flow as it changes over. The solar pump is started by the cold tank sensor and everything is managed by the Steca TR 603 solar controller which also modulates the pump speed to keep flow temperatures up.

With two solar coils in use, a bigger solar array can be used without resorting to the absurd remedy of using an external plate heat exchanger and circulation pump. Absurd? Imagine sunrise, the panels and the pump start up, the tank is destratified and your morning shower is there no longer. Dooh!

 

Heat management

With high grade heat sources connected – a wood burning stove and solar – the hot tank can get very hot. High grade heat is a valuable commodity so the system hangs on to it as long as possible but excess energy will have to be moved eventually. The system does this in 4 stages, each triggered by a cascade of temperature levels.

Destratification  – First the pump for the hot water plate heat exchanger is activated for short bursts. This moves hot water down the tank and effectively increases its capacity.  The process is limited to the maximum return temperature a wood burning stove can tolerate before the back boiler starts to kettle.

Blending the tanks – If surplus energy is still arriving, a valve connecting the hot and cool tanks opens and the cool tank starts to warm up via a thermosiphon. In this way a wood burning stove would provide for masses of hot water first and then go on to address the central heating. The valve sets to open in a power cut and is controlled by the overheat stat for the hot tank.

Overheat thermostat 2 – In the unlikely event of the cool tank reaching 70 degrees, the overheat thermostat starts the heating pump to dump heat to the heating system or a purpose heat-dump fan-coil.

Power free heat dump – As a last resort, and in the case of a power cut, a power free valve in the hot tank is activated to flow cold mains water through a small coil and send energy down the drain.  It is hard to envisage a system where this would really be required but the option is there.

Heat pump integration

The floors pump and the fan-coils pump first draw water from the tank, the repository for free energy. The heat pump runs when the tank temperature becomes too low and then the flow goes directly to the floors or fan-coils. The latter can only be achieved if the heat pump circulation pump flows slightly more than the demand pumps and there are a couple of ways to ensure that. When the heat pump is running under PV energy during the day it will top up the tanks or supply heating depending on demand. Heat pump set points to suit fan-coils or floors will be triggered by the relevant circulation pumps and by the PV output.

Controls

You might imagine that a sophisticated control system would be needed but that is far from the case as many of the functions are independent of each other with only temperature levels causing any interaction.  For example, the circulation pumps for floors and fan-coils are only activated by programmable thermostats and the latter do not call the heating.  The heat pump is timed and only tops up the tanks if temperatures fall enough to call it, otherwise the wood and solar do the job. Destratification and blending are all independently triggered by temperature levels.

Simplicity is a major benefit. Should any problems arise there is no need to call in a specialist expert.

Who makes it?

In the first instance I will help you to specify and match the various elements of the system so that a bespoke specification is readied for production by the British manufacturer.

The system is based on a standard heat store with a few additions and those additions contain nothing new or untested.

Despite the simplicity this is the absolute cutting edge of Eco-heating systems.

Pre-wired and plumbed this is a quick and cost effective way to solve all your heating issues. The successful integration of wood and solar means a smaller and less expensive heat pump can be used with fewer P.V. panels to drive it. Considering all these savings and minimal running costs the Original Twist Eco-heating System is what every new Eco-house needs.

To see if this, or a single heat store, would be suitable for you just use the contact form and we can discuss your requirements.

 

The Original Twist Eco-heating system

Features summary

Stainless steel tanks – should last a lifetime

Total of 1,000 litres for energy storage

One cool tank for virtual stratification.

Mains water pressure is maintained but tanks are unpressurised

No hot water is stored – legionnaire’s avoidance

2 stage hot water heating for heat pump compatibility

130Kw heat exchanger for hot water making – more if required

Hot water circulation

Anti scalding

Suitable for solar input of up to 14kW

Solar stripper circuit for dramatically enhanced panel efficiency

Special large ports for wood burning stove gravity connection

Extra sensor pockets for home automation compatibility

DHW prioritised with energy overspill to heating

Condensing gas boiler optimised – controlled return flow temperature

Heat pump optimised and compatible with other heat sources

Heat pump efficiency raised through extra daytime running

3kW immersion for backup heating

4 stage safety system for energy control

A mix of under-floor heating, towel rails and fan-coils can be used

Fan-coils and a suitable heat pump can give air conditioning

Air Source Heat Pumps and the Renewable Heat Incentive.

The Energy Saving Trust heat pump survey in 2009 found that many users were not impressed at all. The follow up in 2013 improved the results but the final average system COPs of 2.45 (air source) and 2.82 (ground source) were still way below the headline figures quoted for these machines which are going over 4 these days.
What is really good about heat pumps is that they can deliver more energy than they consume in electricity.

The power multiplier

The power multiplier


So a small one would be just like this diagram; working on the power of an electric kettle but delivering the power of 3 to your hot tank – a COP (Coefficient Of Performance) of 3 then. By contrast your immersion heater delivers and also consumes the power of an electric kettle so it has a COP of 1.

Heat pumps are all sold with an industry standardised COP. This is misleading to say the least and the reason why optimism is defeated by experience. Far from being a fixed figure the COP actually swings widely depending on outside air temperature and temperature delivered in the home. The COP plots here show how a kick is engineered to give a good headline figure; that kink in the graph is exactly at the publication point.

A sneaky kink

A sneaky kink


You might buy a machine with a quoted COP of say 3.75 but while making domestic hot water on a cold night it will be working at less than 2. There are benign swings however and given a sunny winter day with some warm air to chew on an ASHP can see COPs almost up to 5.

Gas per kW.hr costs almost exactly a third of electrical power so after adjusting for efficiency a gas boiler is similar to a heat pump with a COP of 3. Many people in the survey would be comparing their new heat pump to a gas boiler; a formidable opponent when running on cheap gas. A gas boiler is much more powerful than most heat pumps and delivers at usefully high temperatures so a heat pump must have an overall COP of over 3 to justify a hefty purchase price and compare favourably.
To be fair the Renewable Heat Incentives state that heat pumps are suited to people without access to town gas. So for them heat pumps are suitable but perhaps the performance could be lifted further?

To winkle out some ideas we’ll take daily temperature data for January in Guildford (http://www.wunderground.com/) and relate that to a COP matrix made from the published data from a modern ASHP (inverter drive scroll, r410a, delivering to under floor heating at 35 degrees).
We will be looking to lift the COP by running the ASHP at the warmest ambient temperatures possible.
A look at a January temperature trace shows:
There is usually a 5 degree swing between the mean night time temperatures and the daytime mean.
Night time temperatures are flatter and longer than the sharper daytime peak at 1-2pm.
The morning transition from lows to highs is halfway there by 10am.
Temperature rises coincide with sunrise, not surprisingly.

Relating the above to the COP matrix:
Running a 7hr shift from 10am gives an average COP of 3.86 – much better than gas.
The equivalent night time shift only gives a COP of 2.92 – but almost as good as gas.
If the pump has to make hotter water for radiators these day/night figures drop to 2.7 and 2.11 and for 55 degree hot water making 2.3 and 1.85– gas beats this hands down.
Storing daytime running means that delivery temperatures probably need to be around 50 degrees leading to an average COP of under 3 although bigger storage tanks improve this.
ASHPs can be smaller if they run continuously day and night on an average COP of 3.4 – still 13% better than gas.
Direct electrical heating is often used to boost hot water making (COP = 1) and this can lower the average COP. If we can avoid this practice and run predominantly in the daytime it should theoretically be possible to get a COP of 3.35 (7hrs day, 2hrs night, 2hrs hot water).
Transmission: Put 100W/square metre through your floors and your feet will be uncomfortably hot so somewhere near half that will be a good yardstick for calculating the power you need to heat the floors then leave some surplus to top up a tank.

Conclusions
A small ASHP can run considerably more efficiently than a gas boiler in a modest well insulated house. Fan-coil units in bedrooms and underfloor heating elsewhere are essential. The heat pump should run in daylight except maybe for a boost before dawn to guarantee morning showers and take the chill off the floors.
I should just mention one little thing in favour of the heat pump; the RHI incentive of 7.3p/kW.hr pitched to pay for the heat pump itself after 7 years. You’ll need to spend another £4,000 on proper tanks to integrate any other sources such as a wood burning stove and a combination like that would be a joy for anyone living out in the middle of the country.

Of course if you make your own electricity, or you want to be green, then a heat pump is already the answer.

The Heating Blog

Heating News                                        Autumn 2013

Electrically charged edition

In this issue:
Electricity Audits – proving popular
LED bulbs – staggering savings
Cheap electricity for heat pumps – new model
PV solar revival – net metering
PV + Heat pump – free heating

Electricity bills audit
Here I take a years worth of data off your bills and the numbers are crunched and graphed on my P.C. to reveal a remarkable amount of useful information:
Average cost of electricity – are you in line with everyone else?
Seasonal variations – shown clearly on the graph, highlights pool pumping, irrigation.
Day use vs. night use – also graphed
Average power used per day and month
All this is analysed in the context of your situation and a comprehensive document then presents the results with recommendations for improvements.
Potential savings have ranged from €5,000 to just a few hundred but they always substantially exceed the cost of the survey. Prices start at €60 but if there aren’t any savings to be made then I won’t charge at all.

LED light bulbs
You might think you’ve done the bulbs thing by buying a few eco bulbs; those curly things that take ages to warm up. Things have changed now because LED bulb prices are falling. For similar money to a curly bulb you can now replace an old 60W bulb with an 8W LED, so 7 times better. They commonly come in sizes down to 4W as well.
A rule of thumb has emerged from the electricity bills audits:
Every 1W used for 8 hours a day costs €1 a year. So roughly speaking Watts are Euros.
So. Say tonight you have 20 light bulbs on at 60W each that’s €1,200 a year. The same set on LEDs would save the €1,000.
Fancy a scary movie tonight: walk round the house and count the Watts – don’t scream at the outside lights.
I think the time has come to start buying LEDs. They come in all the usual fittings and there are some neat little GU10 and saucer like GX53 fittings for new installations.

Electricity tariff for heat pumps
For the audits I’ve had to build a model to study the effects of changing over to the special Enel BTA3 tariff for heat pumps. The heat pump has to be independently supplied with its own meter and while the fixed costs are a bit higher the running costs are lower.
The surprise of this exact modelling is the way the original D3 bill is not only reduced because of the heat pump removal but the expensive end of the bill is top sliced to give a lower average charge. Savings range from around €500 for light users to several thousands for heavy users. If you have, or are considering, a heat pump then I’d suggest you get your numbers crunched on this model.
My main integrated heating model which compares and prices all inputs on a seasonal basis now incorporates this tariff and effectively adds all electricity costs to make a totally comprehensive energy prediction. For example the seasonal power requirement curve for your house can be matched by a stack of sources including solar thermal, wood, PV, and ASHP and all these can be juggled to arrive at the best heating strategy for you.

PV solar revival
Early investigations of the new net metering scheme look interesting and for some users PV is a runner again. Net metering is pretty basic. You benefit from the free power you consume and any excess is effectively exported and stored for later consumption but subject to a handling charge.
Because the cost of electricity has risen so sharply over the last 5 years the savings are rather like a generous feed in tariff equal to the cost of buying electricity. That is to say that the panels make around €0.33 per kW.hr if you would otherwise have paid for that electricity.  The benefits vary a lot depending on the size of the array relative to your normal consumption. Users with a consistent day time load, such as a heat pump charging big water tanks, will benefit most. To get a grip on where the boundaries are let’s take a 5kW array costing €15,000 and assume that all production is consumed with nothing exported. For central Italy the defrayed electricity bills are worth just over €2,000 so the upper limit for returns is 13% tax free. With heavy summer air-con and pool pumping you might get close to this, otherwise it starts to look less appealing. If you pay tax in Italy then grants are available on the installation and the whole plot looks much more interesting.
For PV anywhere in Umbria or Tuscany contact me for help with the appraisal and installation.

PV plus heat pump
We’ve seen how the constant load from a heat pump can make the PV prospect more attractive so let’s flesh out the scenario a bit with a real world example. A 6kW array in winter sunlight would match the 2.5kW consumption of a small 7kW heat pump on a realistic COP of 2.8. The heat pump would therefore heat some 100 square metres of floor space, free of charge, for about 5 hours on 3 out of 4 winter days. There are night hours too so only half the bill will be met but the saving for a typical house will be €1,000. If you like to fire up a stove in the evenings this scenario is the best you can get without doing masses of log lugging and particularly suits anyone working away from home.

Heating Italy  –  News                      Spring 2013

Next Seminar – March 18th       Start time 9a.m.
There a couple of places already booked so please secure your place now if you’d like to come.
This is an intensive day going through all aspects of heating and energy and by the end of it you will feel very confident about what you should be doing and why. It’s also quite fun with a small group, chatting over lunch etc. As well as improving on the usual accepted heating practices we look at:
• Stacking power sources
• Estimating power requirements
• Modeling -what power sources- with your annual bills calculated
• Building better solar profiles with various panel angles
• Heat pumps – what are they really like?
• ASHP – enhancing the COP – better ways to connect a tank and a heat pump
• Pool heating and eco-filtering on 200W of pump power
• Introduction to home automation and security
• Specific attention to delegates own projects

In this issue:
Free air conditioning
How to burn wood
Hot water circulation
Zones – the first economy trick
Old house zones impossible?  Not really

Free air-conditioning
The chart for the average high and low temperature range for Perugia shows a significant drop at night. Even during the hottest nights the outside air is cool enough to be used for extra house cooling. The night temperature is often around 16 degrees with a brief rise towards 20 degrees in August. These temperatures would call for the heating to be on if they were inside the house!  Cooling the house with this chilly air couldn’t be easier although we need to shift a lot of air to make a difference.
The simple DIY solution is to take a north facing downstairs window (with mosquito netting and security bars) then use an ordinary desk fan on the windowsill to pull in cold air at night. Make sure there is a similar vent upstairs for the displaced hot air to escape.
A simple timer plug would set the fan running every night but if you wanted to go one step further on the control side then a simple solar controller could run the fan whenever the outside temperature sensor was cooler than the inside one.

How to burn wood
No seriously!  If I put a moderately big log into the middle of my stove the carcass thermometer drops from 300C to 200C.  As heat transfer is proportional to the excess temperature of the surroundings (say 20C) then this is a 35% drop in heat output and it feels like that too. So what is going on here? Well it’s the water in the wood consuming latent heat as it turns to steam at a paltry 100C. Until that water is cooked out the fire will be suppressed, and very inefficient, as many of the tarry creosotes don’t burn in those cool, moist conditions.  To keep the fire really hot it’s best to feed wood in at the sides where it can toast dry for a while without cooling the hot centre. The drying process can also take place outside the stove if the wood is stacked around the stove for a while. Have a go at this and you’ll find your stove seems to be better straight away.
The chemical reaction also spools up better with more burning surfaces reflecting heat onto each other so many smaller bits of wood will make a big difference too.
There’s a technique for re-starting the stove in the mornings worth mentioning:
just 2 or 3 small glowing coals from the night before will be fine. Scrape a small pit through the ash just big enough to hold the coals and all the way through to an opening in the grate. Knock the coals into the hole and throw a small handful of kindling dust and small wood chips on top. Now with the doors closed and only the grate vent open a draught will come up from the grate to fan the coals into an instant blaze to catch your dried morning sticks …  so quick you can get it done before the kettle boils.
One way to ensure there are some coals there in the morning is to leave the fire burning on one side only with a stack of heavy logs on the other side waiting to catch later. Not too many logs either or the fire will get very hot and burn everything out before morning.

Water circulation
This is about circulating domestic hot water around a loop so that any connected tap has a nearby source of instant hot water. No wasted time and no wasted water down the drain while you wait. 
The loop is constructed by returning the flow to the heat source after passing the last tap or shower spur; simple and cheap enough. A small pump on the return side maintains circulation. This used to be the province of big houses but as we seek greater efficiency and water conservation it will become more mainstream and probably compulsory for new-build houses.
There are a few choices when it comes to the ways of controlling the system. As it would be inefficient to run it all the time there must be some control in place such as:
1/. A time clock on the pump runs it at times when you might need hot water. This is outdated and only suited to people living on a strict time schedule. The timer needs resetting whenever leaving the house unattended although it can be left on for useful frost protection.
2/.  A pressure or flow sensor starts the pump on first use and then times out after a few minutes. Very economical but you need to remember to give a hot tap a quick run before your shower by cleaning your teeth first for example. I love the idea of starting the pump with a movement sensor in the bathroom and having the lights turned on at the same time. Visitors never know where the bathroom light switch is and they’ll appreciate having instant hot water too.
3/. Grundfoss sell a smart pump for circulation. Not only does it slow down when the return flow is hot enough but it starts when any flow is detected and then learns your regular habits to pre-empt any future demands.
4/. If you extract hot water from a heat bank via plate heat exchanger then circulation is less simple because the hot water is being pumped out of the top of the tank and sent to the bottom even when you are not using it. The most sophisticated heat extraction units go as far as returning the flow nearer to the top of the tank when it is hot and only to the bottom when it is cooled through use. They also reduce the pump speed so they have all the bases covered, but at a price. Expect to pay up to €2,000.
5/.  My DIY solution.  A Steca module is available to start and stop the pump. Use a Grundfoss Alpha2 pump or similar and a temperature limiting valve to throttle the return flow when the required temperature is reached. When the return flow slows then so does the pump and economy is preserved.
(The latest Steca controllers also regulate the pump speed so the flow limiting valve is not required although a flow/temperature sensor is required instead)

As you can see there are many ways of circulating water – you’d think a simple thing would have a simple solution.

Zones – the first economy trick
While it might seem rather obvious that you only need to heat the rooms you are using this logic has by-passed a few installers and one still sees houses where the heating is either all on or all off. Usually a gesture to efficiency is made by having thermostats giving separate temperature control of upstairs vs. downstairs but no more.  What is lacking here is time control so that you can decide when the temperature control is applied and crucially, when it is not applied.
Efficiency, economy and comfort can be hugely increased very quickly and cheaply in most cases.  All that is needed is to change the old thermostats for programmable ones so that they introduce time control as well as temperature control.  With this simple change the downstairs heating can be set to go off shortly before you go to bed and the bedrooms heated in advance, and vice versa in the morning. With such tight control those thermostats could recoup their cost in the first month.
For simple installations my favourite progstats are the Btcino L/N/NT4450 which are easy to set and give 48 on/offs a day and so can be fine tuned in half an hour increments. For a more sophisticated approach see below.
I believe current regulations ask for each bedroom to be separately zoned with individual thermostats so if you are building or restoring then this is a must.

Rectifying old houses in need of zoned heating.
If your old system consists of a series of radiators that are all on or all off with maybe just one thermostat, or even none, the situation can still be remedied.
What you do is to make each radiator a zone by changing the radiator thermostatic valve with a programmable one. These are neat little things and cost about £25. 
Going one step better have a look at the radio controlled version from eQ-3 MAX where you can adjust a thermostat module on the wall.  All these can be found very cheaply on http://www.conrad-uk.com/ce/en/overview/0812043/MAX-Heating-Control-Systems 
Going even further one could fit Z-Wave radiator thermostats all round and control them from your i-phone. Whatever you do it’s good to know that an old house can be made as tightly controlled as any modern one.

Heating News                                        Autumn 2012

In this issue:
PV – a narrow window remains
Clearview stoves – prices held
New heating model
Wood – how much?
Air source heat pumps gain popularity
Winter safety
Seminar – October

PV – a narrow window remains
I rang ‘last orders’ on PV in the last newsletter and as the GSE quota got progressively taken up it looked last week as though the end was under a month away. However as we near the end the rate of take up has declined with the calculated end day now pushed out to 155 days. That will fluctuate but the odds are that, perversely, it could even increase as the probability of a successful application decreases or appears to decrease.
So if you are in the market for a PV installation here’s what the situation looks like:
The plug has been pulled on ground installations – no more huge PV farms but also no little ones in your garden. It’s just roofs and car ports from now on.
My PV installers take a sensible approach. You pay them (and risk) €421 for comune surveys and fees and they do their best to beat all the deadlines for you. They do a lot of work to push all this through so it’s a big loss leader for them at this rate.
The feed-in tariffs have all changed again and now a payment is made for power exported and a lower rate paid for your own consumption. This looks a bit strange at first glance but you are effectively paid for all production with a reduction penalty for consuming some of it.
Plant costs continue to fall and the payback period remains at 7 – 8 years although of course the power for money ratio is at an all time high. As energy prices rise the payback time will fall of course.

Example guide prices inc IVA: 
€8,580 for a roof mounted 3kW with a total return of €1,000 a year.
€13,000 for 6kW so some economies of scale here.
€ 14,000 for a 4.6kW car port.

Of course there may be another regime when the current tranche ends. There is talk of it being based on tax rebates though so for most expats it will be a non starter.

Clearview stoves – prices held
The price list is issued in January and last year it was left unchanged giving us 2 years of stability.
I doubt if they will hold prices in January 2013 so if you are contemplating one now is the time to give me a call.  As ever the 750 flat top is the most popular for water heating applications and the Vision 500 for stand alone installations.

New heating model
My new model, running on my PC, continues to be useful in evaluating various mixes of heat sources and making a fuel bill prediction.
With more heat pumps being considered there is an interesting new slant on solar thermal panels. When compared to gas power they were saving something like €600 a year but compared to an efficient heat pump they only save about €200.
So with a limited budget would you spend say €3,000 on some panels or €6,000 on an installed air source heat pump? Not such a no-brainer any more is it?

Wood – how much?
Did your wood run out last winter? If so how much does one need to get through another cold one?
A regular stone family house here needs 25,000kW.hrs of heat and 90 quintale of dry wood should do the trick. That’s about €1,000 worth but a lot depends on how dry it is when you buy it.
To be sure of dry wood you need to buy before the summer baking gets going then the wood will lose around 25% in weight. So yes you bought €250 worth of water and you no longer have as much wood as you thought. You could argue this point with the wood man but to be sure of being warm you should always over order and a safer quantity would be 120 quintale.
My test log has lost 22.27% in weight since it was delivered on 10th July.
If you have another heat source then you can cut back on wood and the chores that go with it. I always set a 14kW limit on stoves as any more turns you into a full time log lugger.
An air source heat pump running on PV power is not far short of the cheapness of wood energy so a combination of the two makes for a more comfortable existence without breaking the bank.

Air source heat pumps gain popularity

7kW heat pump from Aermec

7kW heat pump from Aermec

Maybe the heat pump open day last April has raised awareness because one no longer has to explain what they are these days. As the cheapest energy producer next to wood the air source heat pump is well on the way to ousting pellet stoves and other unworthy competitors.
Meanwhile, back in the workshop, we have made a bit of technical progress on the way heat pumps are connected to tanks and how they can be integrated with other heat sources. A couple of simple changes allow the top of the tank to be top loaded for rapid domestic hot water extraction and a subtle connection enables the under-floor pump to use both wood heated water and heat pump water without disrupting the tank stratification. This might sound boring but I have seen no signs that the rest of the industry know what the problems even are let alone how to solve them.

Winter safety alert
The Beeb site recently had an article on exceptional glacial melting going on right now making the 2012 records show that something really different is under way. Glaciers sliding on melt water can charge downhill at 40m a day. Some scientists believe wetter summers and colder winters could accompany this and judging from last year perhaps we should all take note and make sure we are as safe and comfortable as possible this winter.
For my part I have been paying particular attention to future and existing wood based heating systems to make sure that in the event of a power cut there will be a base line of heating and cooking facilities. Systems with electric circulation pumps are especially vulnerable to power cuts and I now have a standard addition to circuits to make everything work.

Apart from that I’ve started a list of things that might be life savers in the event of a prolonged snow-in with possible power cuts.
Stock up on tinned food, pasta, cheese and bottled water
Check your medications if necessary
Stock up on all household consumables
Buy extra pet food
Stack a stash of wood near or in the house – 3 weeks worth
Buy a battery charger for the car and plan how it will be connected.
Get diesel additive before it runs out
Top up gas tank, pellets etc
Buy a snow shovel
Order a load of DVDs and books
Build up wine stocks.
Candles, torches
Tilley lamp – Coleman petrol lamp is fantastic.
Get good footwear – boots
Top up mobile phone

Heating Italy  –  News                December 2010

In this issue:
The final nail for gas boilers                        … turns out you don’t really need one
Retrofit immersion heater                                                     now anyone can fit one
Heating system built in simple stages                        start simply then keep adding
Air Source Heat Pump                                            time to bin the gas boiler – again
How to buy and burn your wood for more heat      where the power disappears to
Photovoltaic on test                                            yes, it works and yes it was worth it
Clearview stoves in Italy                                                 at last you can buy one here

Death of the gas boiler?
Our standard formula for very cheap heating in Italy is a wet-back wood burning stove, some solar panels, all hooked up to a heat bank. Technical progress this year has led to editing out the gas boiler in many systems. Already the boiler was pretty much relegated by the stove in the winter and solar panels in the summer and now just 3 small changes have made the gas boiler redundant in many installations:
1/. More bias towards water heating on the stufa. A bigger back boiler cuts the recovery time on the heat bank so the hot water is always there. With a little seasonal help from an immersion heater there are very few gaps left where a gas boiler would be useful.
2/. Bigger solar panels. Three layers of safety enable our big 450 litre heat bank to handle around 7.5 square metres of panel especially if they are tilted steeper for an autumn/spring bias. Steeper angles give a much flatter and fatter production curve which helps the solar panels match all the hot water demands well into the shoulder months without overheating in the summer.
Oversized panels connected directly to the heat bank also enable pool heating with any of the other connected energy sources. There is a useful Excel model on the www.heatingitaly.com web site for calculating solar panel energy around the Perugia area. You can also get the ‘Heating Guide’ on the web site – ask me to e-mail it to you if you can’t download it.
3/. Immersion heater.  Not seen much in Italy – where using 3kW of electricity is deemed excessive – immersion heaters are surprisingly useful and in practice punch well above their weight. The cost of use is similar to gas but the £56 capital cost of the heater on the heat bank is trivial compared to a £2,000 gas boiler with extra for a flue and servicing.
There will only be a handful of days when neither the stove nor the panels are producing enough energy. Tests this, rather wet, autumn found that running the immersion heater for a mere 4 hours a day was enough to keep the showers flowing hot until evening use of the stove took over.
If you have PV solar panels then immersion heating is a complete no brainer. Use some free power to top up the tank in the middle of the day. Alternatively without PV assistance the heat bank is best heated on cheap night time electricity when there are no other appliances running.
Bear in mind that there are only about 2 months when minor electrical top ups are necessary; otherwise wood and solar are enough.

Retrofit immersion heater
If you have an existing tank without an immersion heater boss there is no need to go without immersion heating. Just mount a remote immersion heater on the side. It’s easy to fit and works on a gravity circuit. In some ways this is the best way to do the job anyway; a plumbers’ nightmare is the seized up immersion boss where the tank itself tears open rather than let the heater unscrew.

Heating system built in stages
There have been a couple of low budget projects this year where the inherent simplicity and cheapness of the heat bank approach has made the job much quicker and simpler. As the heat bank comes fitted with all the pumps, regulators and controls for a complete system it is very easy to ‘plug and play’. Just connect some 10 pipes and everything is ready to run. Connecting solar panels, gas boiler etc can be left until later as the immersion heater is enough to get the house going for an immediate summer let. As the plumber has little to buy (and mark up) and many hours saved, the plumbing bill should be greatly reduced even to the extent of making the heat bank effectively free. All the other heat sources can then be added, when needed, with minimal disruption.

The heat pump era has arrived.
2010 has seen heat pumps gaining ground, particularly the cheaper and simpler air source pumps (ASHP). We have seen the arrival of several new, compact and efficient ASHPs running the latest R410a refrigerant. Some vendors are still charging premium prices for out of date models so take care if you buy.
In Italy, energy from electricity costs about the same as gas. A heat pump can produce between 2 and 5 times as much power as it consumes and this makes it inherently very cheap to run. In fact a heat pump running on PV panels will compare well with a wood based system. A smaller modern, well insulated house needs so little power that cheap, low powered ASHPs will replace gas boilers over the next decade. Chinese models, using many European and Japanese components, are available for around £1,000 so the outlook for gas boiler manufacturers is starting to look bleak.
Modelling of ASHPs running at optimal times such as warmer days or cheaper night time tariffs show the need for large heat banks as buffer stores so if you are planning a new house leave some space free for a couple of tanks.

Burning issues
This is a typical story.  In September or October John remembers to buy 100 quintale of split wood for 1,200 Euros. As usual, to save on handling, the wood was sawn and split and sent up the conveyor into the truck just before delivery. Whole trunks don’t dry half as well as split logs so the wood was still wet with 30% water. John had bought Eur 400 of water, but his troubles were only just starting.
While the fire boiled the water out of the logs it burned cooler and John’s 84 quintale of actual wood produced only 3.4kW.hrs per Kg. This produced 23,800kW.hrs of heat – slightly short of the 25,000 his house needs. If John had stacked and dried wood from the season before it would have dried to below 20% and he would have got over 4kW.hrs per Kg. That’s about 23% more power; 2,900kW.hrs which is more than he would need, leaving some left over for next year.

In extreme cases the difference in energy production between very wet and very dry wood can be over 50%.
So take note. Don’t buy wood at the last minute. At the very least buy it in the spring and sun bake it all summer. Buy more than you need to start getting ahead.
The way you burn the stufa can make a difference too. Wood burning very hot will burn off the tarry creosotes which gives more heat and keeps the flue cleaner. If your wood is wet, try to keep a pile next to the stove to dry out and then feed it in at the sides of the fire to dry more while the fire burns hot in the middle.
Being mean with one sad log smouldering away is false economy. The fire needs to be very hot to burn efficiently. This means you should never buy a bigger stove than you need.

Case study PV solar panels.
Our 4.6kW car port is still coming towards the end of the first year but already the result is taking shape. Roughly, one could summarise the story by saying that there was just about enough production to pay the bank interest on the loan and electricity bills were eliminated despite a decision to use more for water heating. Gas boiler use has consequently dropped to about one ten minute boost per month for unscheduled top ups.
The case for borrowing looks rational. The bank made us deposit 10,000 Euros in a fund which historically yields about 5% and we save well over 1,400 Euros a year in electricity and gas bills, effectively adding another 14% yield on the refundable deposit. Of course the production meter is earning too but the bank gets all that. While everyone else’s bills keep climbing ours remain fixed until eventually the bank gives us back our money and we keep further production payments too.

Income from a 4.6kW array

Income from a 4.6kW array

If you work out the cost of not doing this you would be shocked at the difference. Many will see their whole retirement fund vanish under rising energy costs while the ones who took the plunge could actually retire on the proceeds of a large PV array.
An unexpected boon comes from the quality of the power when the sun is shining. It took a while to figure out why the toaster worked so much better at the weekends!

Money earned is proportional to power produced. Note the huge differences across the year. The monthly totals show that the panels almost never produce near their rated output; one third in winter and two thirds in summer is more like it.
Clearview stoves in Italy
These stoves are popular for a very good reason. The quality is outstanding and they work reliably for years without cracking up and leaking. Clip in back boilers are available and if needs be can be replaced easily without writing off the whole stove.
Demand in Italy has been consistently high so the time came to start importing them to order. The first batch arrived without a hitch and very robustly packed.
Currently the most popular model is the 750 flat top which develops a useful 14kW and is even good for cooking on.
For a small modern house the Solution 500 is well worth a look with a pleasing combination of tradition with modernity. Dramatic polished stainless steel sides can be ordered to replace the ones shown here.

Clearview 750 - 14kW

Clearview 750 – 14kW

Heating Italy  –  News                          Autumn 2011

In this issue:
Special offer                                                                    the ‘Italian Job’ heat bank
Clearview 750 stove                                                  pricing up the perfect partner
Changes – too late for winter?                                        not really, if you start now
PVmarket in disarray                                         the sensible approach to take now
Heating seminars                                             next one Thursday September 22nd
Pool heating                                            cheap and easy to add plastic solar panels
The solar circuit                                                  easier and cheaper than you think
Oversize solar arrays                                                       a new angle on the subject
Remote immersion heater                                                         quick and easy to fit
Wood burning air cooler                                               don’t tell me you’ve got one

Heat bank review
First of all, DPS heat banks are no longer sold under that name. The company is now run by Specflue, a much bigger and more stable company. Apart from a price hike everything else is the same. The same product is made in the same factory by the same people and is still the best of its kind in Europe.
All the heat banks we’ve used in Italy so far showed that the only big variation in specification was whether under-floor heating was needed or just radiators. So to simplify matters here is the ‘Italian Job’ standard specification with the under-floor heating module offered as an extra.

Specflue 475l heat bank

Specflue 475l heat bank

        Italian Job’ Specification:
    ‘• 475 litre stainless steel tank rated for 10 bar   663mm x 2,000mm – even good for tall tobacco towers.
• Heat exchanger (160kW) and pump for domestic hot water – pure hot water instantly generated.  45 litres\minute is good enough for simultaneous showers
• Hot water temperature regulation – prevents scalding from extra hot water.
• Pumped outlet for radiators and towel rails – use the same line for pool heating too if needed.
• Single channel programmer + thermostat – to call a gas boiler or an alternative
• Temperature regulator assembly for gas boiler connection – corrects return temperature to boiler.
• Wood stove ready – extra large ports for connecting a wood stove or furnace
• Solar ready – just add panels and a pump station to go solar
• Heat pump ready – diffuser on under-floor boss prevents turbulence
• 3kW electric immersion heater – with robust timer switch wired in.
• Thermostat for over-heat protection – turns on radiator pump to dump excess energy.
• Solar coil and sensor pocket – just add 2 to 4 panels and a pump station to go solar

Special offer – this spec for £4,288 inc. VAT and delivery to Central Italy. That’s 10% off the factory price and free delivery!

Price with under-floor heating module – includes pump + temperature regulator. For direct connection to UFH manifolds.
£4,788 inc. VAT and delivery to Central Italy.

This offer will be held until the end of November unless any significant price changes come from the factory.
Clearview 750      www.clearviewstoves.com
This fabulous stove is such a good partner with a heat bank that they are often ordered as a matched pair. I have written enough before on the stove so we’ll get straight to the pricing which is shown inclusive of VAT and with some recommended extras. There are a few colours to choose from but so far everyone has gone for green. Black is the cost free default. Transport will vary depending on what else is coming over, for example with a heat bank the stove could be tucked on for nothing. Let me know in good time if you want one brought over.
    Clearview 750 flat top        £1,718
    7kW clip in back boiler       £300
    Colour                                         £54
    1m stainless flue                     £87.73
    Export crating                         £65
    Total                                          £2,224.73

 Too late for Winter?
You’d be amazed how quick some installations can be. As the heat bank comes as a complete plumbing system – with all the pumps and wires connected – there are only some 10 pipes to connect up in the technical room. The modular nature of the system means it can be used immediately for hot water delivery just by turning on the immersion heater. A wood burning stove, near the heat bank, can often be connected with just 2 pipes and no pumps and controls.
The solar connections can be left for later as they won’t be of much use until next summer.
So if a cosy Christmas in Italy appeals you have 4 clear months to get the job done. 2 to get the heat bank and wood stove out here and another 2 to get them plugged in.
Christmas is often the big marker for the real start of winter. Until then an evening light up of the stove with occasional days is often enough to keep things cheerful.

Heating Seminar
These days are limited 6 people so there is always plenty of time to talk over individual projects.
If you need to stay we can offer accommodation.
The next seminar is on Thursday 22nd September.    See you there?
Seminar dates are set fairly arbitrarily. If you have a date you can manage let me know and I will see if I can build the next one on that.

“I can’t thank you enough.  I can honestly say that by attending yesterday, you have saved me from making a couple of very expensive mistakes with my renovation – one of which would have precluded me from being able to install this system, which I so very want.  Some gems of wisdom and real-life experience is worth its weight in gold”
 
Topics will include:
Various heating systems in common use – pros and cons
Heat sources – the best and the cheapest
Heat sources – installing stufas and solar panels
Safety – how to keep yourself and your guests safe as well as warm – with exploding boiler film
Heat banks – the key to success, how to integrate and manage everything simply
The cost – low pay back times are essential and possible
How to plan your project – matching supply to demand (technical issues)
Photovoltaic – why it really is worth it
Heat pumps – overview and costs and where they are heading
Common mistakes and how to avoid them
Pool heating – the sensible way – & pumping for 200Watts
Real case studies
The best kit and where to get it
ZERO GAS?  … usually quite easy   ZERO COST?  …  maybe even a profit

Pool pumping? – add solar panels
Since the write up in the last issue, demand has been high for the magic low energy pumps. No wonder; at €1,550 and old pumps costing about €150 a month to run the payback is around 2.5 years.
As fitting is usually a quick swap-over with the old pump there is an opportunity to add some plastic solar panels to the circuit at the same time.
A set of four panels costs about €1,200 and will significantly extend the swimming season.
Often fitting is as easy as chucking them on the bank by the pool house.
Like all panels we only want them to work when they are hotter than the pool so a solenoid valve is needed in the new circuit. A Delta-T controller tells the solenoid when to pop open.

The solar circuit – easier than you think.
Given a tank with a solar coil the rest of the installation is easier and cheaper than most people imagine. There are only 3 elements in the pipe loop. The solar panels at one end of the loop, the solar coil in your tank at the other and a combined pump station and controller to make it all go round. The easiest DIY solution is a ground mounted array screwed onto pre-cast concrete blocks. You can buy special insulated tubes or16mm insulated copper pipe on a roll is easily obtainable and after foaming it into bigger plastic tubes it can be laid into a trench – just don’t forget a pair of 0.75mm section copper wires from the sensor on the panels to the controller. Another sensor goes from a sensor pocket on the tank to the controller.
Once the circuit has been constructed and pressure tested with air you can fill it with solar fluid. A garden weed sprayer is perfectly capable of pumping the circuit up to 3 bar.
Roof mounted arrays can be more involved as often they have to be integrated rather than over mounted.
Costs? The starting point is about €2,500 which should set you up with a couple of panels and a pump station along with some tube and fluids. Gas powered summer hot water costs vary around the €600 mark so the pay back for the panels is about 4 – 5 years.

Oversize solar thermal arrays
The sun has no off switch! The biggest problem with oversize arrays is that in the hotter months a huge surge in energy has to be dealt with and often jettisoned. A swimming pool is a handy reservoir for heat but even that will be hot enough by August so energy might have to be dumped to a radiator, ground tubes or poured down the drain.
It is often overlooked that the solar coil in your tank has a limited transmission capability so while we welcome masses of solar energy in spring and autumn it would be better if the panels would work less efficiently in mid summer. Luckily we can achieve just that by setting the panel angles steeper to suit the shoulder months and tame the hot ones.
The diagram shows how a 7.5 square meter array at 30 degrees can be enlarged to 10 square meters at 60 degrees to give the same peak delivery but a much wider production curve with a good extra month of useful production on each end. When the winter sun is really low the panels are in their element with relatively huge gains in useful production. For an idea of what this power represents there is a line across the graph to represent the power of a gas boiler running for an hour a day.
It is relatively cheap to add 1 or 2 more panels to an array so for ground mounted installations, where the angle can be chosen, this is really worth doing.
Have a go with the panel angles spreadsheet on www.heatingitaly.com to check out your own ideas.

flatten the solar production

flatten the solar production

Remote immersion heater
A local supply of 1.5” screw in immersion heaters has just made it easier to construct the remote immersion heaters that can be retro-fitted to most existing tanks. Now an insulated 3kW remote heater can be yours for just €110. A pressure release valve is incorporated in the design to prevent anyone from closing off the valves at the tank and then boiling up and bursting the heater.
Connection is usually very straightforward. The heater module is connected by a pipe to the top of the tank and another to the bottom. When the heater is switched on the hot water circulates up to the top of the tank and so produces the ideal top down loading. This is even better than a regular tank mounted heater so if you ever find one is stuck in don’t risk breaking your tank to remove it, just fit a remote.
Immersion heaters are particularly useful for solar PV owners and for anyone else wanting to use the latest cheap night time electricity offer. Compared with the cost of a gas boiler this looks like the best heating bargain ever for domestic hot water production.

PV market – how to make it work
Last April we all waited with bated breath for the new decree on PV solar tariffs. Before the announcement the industry ground to a halt as no one knew what their deal was going to be after the usual months long application period. Ironically the final verdict – wait for it – no change for the time being and the old reducing tariff table still applies. Well thanks for that. Now what should one do? The tariffs are falling on a preset schedule and panel prices are falling too. The return on capital of almost 15% still applies and this is certainly worth chasing despite the difficulties along the way. It is not just the tariffs being changed as different comunes seem to draw on a reservoir of reasons to object. 3 months ago a ground mounted array was an easy choice, car port mounted arrays would take months but now roof mounted arrays are practically instantly granted with the caveat that they have to be integrated in the roof and not over the tiles.
My local PV guys have a good solution to the dilemma. You pay €1,000 for getting the comune permissions, Enel survey, and GSE contract ready and only then, if the tariffs are still satisfactory, do you sign the papers. If not you can walk away having only lost €1,000.
I think this is the only way to go, and the sooner the better, as there is no certainty that this deal will be around for much longer.

Heating Italy  –  News                         Spring 2011

In this issue:
Heating seminars are fun apparently                                        next one May 30th
Pool pumping on 200 Watts                                              surely that’s impossible?
The final nail for gas boilers                           case study gas consumption graphs
Air Source Heat Pump                don’t look now but there’s one in your kitchen
6 kilowatts of free power!                                                       surely some mistake?                
Clearview 750                                                                         featured wood burner
Technical room                                                          turns out you don’t need one
Clearview stove on Sketchup                                 now you can draw the pictures

Heating Seminars are fun
Becoming a regular feature, these days involve no more than 6 people so there is always plenty of time to talk over individual projects. Despite a day crammed with interesting analysis and information there is still time to meet new people and have a good chat over lunch.
Delegates have come from all over Italy – Sardinia is the record to beat.
It’s great to see how to save a lot of money in the future and have fun at the same time.
Later in the day we relax a bit with film clips of badly installed boilers blowing up and new pool pumps running on the power of a couple of light bulbs. Maybe, if there’s time, we fit in a 5 minute stroll over to our Etruscan tomb.
The next seminar is on Monday 30th May.    See you there?
Seminar dates are set fairly arbitrarily. If you have a date you can manage let me know and I will see if I can build the next one on that.

Pool pumping sensation
Your 1.5kW pool pump is costing hundreds of Euros to run so let’s ask why. First the pool man played safe and installed a bigger pump than was necessary. Better for you to have a big electricity bill than for him to have to come back and fit another pump eh?
The pump has 2 main jobs. First we need plenty of power to run pool tools such as cleaners, vacuums etc and also to wash the bugs across into the skimmers. After that comes filtration but using the same power to do this is where the trouble starts. Energy consumption rises with flow as a square law, or higher, so high power filtration pumping is not a good idea. Even slight reductions in flow can halve the electricity consumption. The Pentair IntelliFlo shown here has a permanent magnet motor which is 30% better before we even begin to throttle it back. It can be set to give high speed bursts and then settle into long, quiet pumping runs using a mere 200 Watts. The bottom line is that 70% savings can be expected. You can find these pumps on the net for £1,600-2,000 odd but often we can supply and fit one for £1,500.
Because of the adjustability of the pump one size fits all.

The end is nigh for gas boilers
Over the past 4 years I have monitored gas consumption for our 280m sq farm house. Each year has seen the addition of another tweak to beat back gas consumption. This set of graphs clearly shows the changes. A gas leak made the graphs a bit shaky at the edges but the general picture is clear. Each successive year shows how gas use is reduced.

Despite the 12kW stufa supporting the gas boiler 4 – 10% of a tank is consumed every month of the first year.
The following year we consciously burn more wood and the wet solar panels are fitted – a dramatic reduction is the result.
Next the PV panels allow the immersion heater to be used. Now with more immersion heater use the monthly gas use falls to between 1 and 2% of the bombola (which takes a good €1,000 per top up) so it should now last for 3 or 4 years between fill ups.
Almost all of this now relates to cooking and the gas boiler is largely redundant. That sounds good but you could do better. As discussed in the last newsletter, with a bigger stufa, bigger panels and a bigger tank you really can chuck the gas boiler in the skip.
Air Source Heat Pump (ASHP)
Over the next 10 years these simple devices will be as mainstream as gas boilers are today. It’s time to make sure we all know what they are and what they can offer us, especially as they work particularly well in the sunnier Italian climate.
You’ve already got one heat pump – the fridge. It takes heat from a source – 2 litres of milk, 5 beers, cabbage etc – and moves it up to a higher temperature in order to dump it to the radiator at the back of the fridge. So heat is pumped from a cold place to a hotter place. Some of the heat at the hotter place comes from the fridge motor but most of it comes out of the milk, beer and the cabbage. The energy is moved from air – in the fridge – so this is an air source heat pump. Now let’s scale up the fridge motor, shrink the cabinet and park it all outside the back door. We end up with a machine that can move heat from the air outside the house and deposit it at a higher temperature into the hot tank, radiators or under-floor heating pipes. The service life is similar to a fridge – quiet uninterrupted performance, year after year, with little or no attention. As the ASHP is moving energy rather than making it there is a limit to how much can be delivered compared to how much is put in. The ratio is called the Coefficient of performance – COP. You’ll see claims of 4 or so but the real world results (according to a recent Energy Trust survey) are nearer around 2.5, a lot less but still pretty good. There are a few tweaks to be made on the installation which should restore the COP to 3 or better but I’ll save those for another day.
In the hierarchy of cheap heat sources wood is still king but heat pumps run such a close second they push similarly priced pellet stoves into pointless oblivion. RIP we won’t miss you.

Psst – 6kW of free energy    Want some?
Apparently it’s hard to give out free fivers in the street. It just looks too good to be true.
Here’s another free fiver and it goes like this.

• A typical domestic electricity supply here is 6kW.
• So you would more easily be allowed a 6kW photovoltaic panel array
• This will produce 2kW or more even on most winter days
• An ASHP consuming 2kW, on a COP of 3 will deliver 6kW

• The free 2kW (you also get paid for producing) becomes a free 6kW into your hot tank.

Tarrah!

We are working hard to find the perfect ASHP to partner the 450 litre DPS heat bank so watch this space.

Clearview 750                                 
One of the best stoves in the world
You can buy a tin of biscuits for €10 or a cheap stove for €300 and structurally they have a lot in common but often the biscuit tin will be around a while after the stove has burnt and corroded. Cheap cast iron stoves come next. Cast iron lends itself well to fussy tresses of filigree but has to be bolted up in panels resulting in a leak prone structure which can crack easily. Models that heat water have the back boiler cast directly into the back panel and when thermal stresses finally cause cracks the only recourse is to throw away the stove and start again – a false economy indeed.
There is a big difference between a Clearview stove and any of the above as one would expect for a £2,200 price tag as on the 750.
A Clearview stove is made of thick steel plate; so thick in fact that 4 men struggle to lift a 750. The plate is precision cut and then folded up on a bending machine before being welded up into one solid structure. Channels are incorporated to duct heated air to the door air wash and the whole lot is then protected by fire resistant panels and more steel plates. Doors are double glazed to give a great view of the fire which might be as hot as 700c. The best bit is the back boiler which just bolts in and can be replaced if anything ever went wrong. This is a stove that should last a lifetime.
The Clearview 750 is featured here because it is becoming the mainstay for many installations. With a total output of 14kW it can carry the total heating and hot water load for many of our houses. The 7kW back boiler means that a useful amount of power goes to the heat bank and we can have a nice big stove without overcooking the room. You’d be amazed at how much you can cook on the flat top too.
I prefer to import these in batches (cuts delivery costs) so please give plenty of notice if you want one. I have brochures and colour samples here.
Minimalist technical room
A ground floor cantina is an obvious place to house your heat bank but if you want to have a wood burning stove connected from a room above it will have to be on a pumped circuit. With all the safety precautions and controls this costs at least €2,000 more than a simple gravity circuit so it pays to look for a better location. Ideally the heat bank needs to be very close to the stufa and a few centimetres above it to enable a virtually cost free gravity circuit to work.
The drawing above shows how a corner fireplace is replaced with a fabricated fireplace and a niche to partially hide the heat bank. A plain door over the heat bank makes it all disappear.

A neat variation on this theme (shown here) is to reverse the niche access to the other side of the wall and to cover the heat bank with an airing cupboard. This is particularly suitable when the walls are not thick enough to hide a 66 cm diameter tank inside.