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.


Small, affordable eco-house

State of the art eco-house is easy and cheap to build.

Check Google images for tiny house, small house, eco-house, green living module or just a modern house. See anything you could imagine building reasonably cheaply and easily then enjoy living in?

Here is something to stir the imagination, a concept sketch of the Original-Twist Eco-house. And this is not just an eco-house by name; it is a thoroughly engineered, practically off grid living module where the technology comes first and the house is made to fit it.

On the first floor a massive structurally open space gives adaptable options.  There is space to the left for a huge kitchen diner (7m x 3.5m) or a smaller kitchen and a bedroom/study. Next comes the massive living room (5m x 5m). The raised bedroom platform (4m x 5m) follows and off that a bathroom and an office or child’s bedroom. These are exceptionally large and impressive spaces and with some expensively extravagant oak frames supporting the roof they are characterful too. Everyone loves heavy rustic looking beams and that ‘barn conversion’ look.

Bye the way; as a protest against flimsy curtain rails there would be heavily mounted industrial Henderson tracks. Even Tarzan could be trusted to draw the heavy curtains across the windows or the bedroom section.

First floor layout

On the ground floor a properly large garage at one end and a full height kitchen conservatory at the other, contain a variable layout of rooms to make a separate living unit. Thus the upper and lower floors combine to make a family house or each make fully independent living spaces. There would be no difficulty making a Granny annex or securing some rental income to pay back some expenses. The foundations for the conservatory should be laid from the start to make it easy to add that on later.

Care has been taken to keep the house very basic and thus avoid unnecessary overspends. We want wonderful living spaces and enough cash left over for something special in the double garage. The simple construction suits ICFs (giant foam Leggo blocks with concrete poured in). It makes more sense to stick to ICFs all through; one contractor, less interference and anyway the clever flooring solution that comes with Quadlock ICFs is worth having. The extra thermal mass is a big plus point and also gives good soundproofing between floors. ICFs are particularly suitable for the wooden cladding shown here although the choices are almost endless.

Another cash preserving strategy will be to delay a whole list of things until after moving in.  The sooner you move in the sooner you stop paying rent somewhere else? The ground floor kitchen/conservatory, home cinema, and all the solar panels can all wait until later and the rent you save will help pay for them. Self builders will appreciate the idea of finishing one floor and living-in to finish the other.

A house designed for the hard times of ex-growth Britain deserves a catchy name – we’ll call it The Brexit.
The side and rear overhangs allow the house to fit into a small plot. It can be built to within a whisker of the boundary and yet you can still walk round the outside. The balcony at the front echoes the overhang to give a pleasing uniformity.

The Brexit is quite small which leaves something in the budget for all the latest mod cons like the home cinema, that car in the integrated garage and of course the eco-kit  and the heat pump pod in the garden. It may look fairly conventional (planners note) but the eco-credentials of this house are exemplary.

The south side has plenty of glass which adds to the feeling of space and allows for enough solar gain to take us into passivehause territory.

Of course the eco-technomologicalness will be state of the art, not just token gestures as in many eco-houses but the highest expression of the art. The 24 Sunerg hybrid solar panels actually dictate the size and shape of the roof and the roof trim panels are fixed directly to the panels (PV and wet solar are both 2m x 1m).  4 of the panels on the steep roof will be wet to give a massive 8sqm to feed the Original Twist twin tank heat bank design. If you are involved in creating anything remotely like an eco-house you should study this system here. The other 20 panels give a nominal 6kWp and a real 2-3kW in the winter to run the little air source heat pump which also does some neat heat recovery from the house and uses some ground heated air too.  Batteries make a huge UPS which largely makes the mains supply more like a backup especially if combined with the batteries in the electric car. The Brexit is designed to be future proof as much as possible. More detail can be found in the e-book ‘Dream House – Down to the Details’ here. Don’t start any project without investing £2.45 on this book.

To convert the living space into a dining room the table comes up from the floor – (see the design here)…… the TV disappears behind a roller cover and the sofa glides back into the recess behind it; fanciful maybe but it makes excellent use of the space and easily accommodates large dinner parties. The sofa mechanism is quite simple with the sofa parking on top of the cover door when it is deployed. The table concept is equally simple but pretty spectacular in action and the small extra cost effectively produces an extra room.
With all the clutter cleared away there is plenty of room for partying with the ‘bar height’ raised platform making a safe place to put food and drinks. This house really is an entertaining machine.

And what a super house to start the day in.  A cuppa in bed on your lofty bedroom, as the heavy curtains automatically retract you watch the morning news on the big screen; time for showers then a sunny breakfast downstairs before nipping through to your dream car. The garage doors rise automatically and you are off on your day.

How much roughly? 188 square metres at £800 is around £150,000. £25,000 for the eco-tech and heating systems, so maybe £180,000. Call it £200,000 plus the plot cost. Looks like a lot of good living for the money, and don’t forget, this versatile house has considerable earning power and almost no running costs. Think clever, think Brexit.

More on this topic in LIST OF POSTS

Tiny Affordable Eco house

Tiny Affordable Eco house

view - South side

view – South side

Eco house from the end showing garage door

Eco house from the end showing garage door

Check Google images for tiny house, small house, eco-house, pod, green living module or just a modern house. See anything you could imagine building very cheaply then living in?
Here’s the Original Twist idea of a simple modern looking house which, by using blocks or ICFs for the first floor and SIPs (structural insulated panels) on top, is quick and correspondingly cheap to make. It is also quite small which leaves something in the budget for all the latest mod cons like the home cinema, a nice car in the integrated garage and of course the eco kit – 24 solar panels and the heat pump pod in the garden.
The actual building is conventionally cubic, clad in vertical wood, with all the metallic looking curvy edges added on later. The edges conceal wires and pipes and are made of polystyrene or zinc covered forms. The upper south side is nearly all glass which adds to the feeling of space and allows for enough solar gain to take us into passivehause territory.
Small it may be but it is huge inside with the main living area 6m x 10m and a similarly massive room downstairs, both with cavernous ceilings. The raised bed platform gives a visual separation from the seating area and allows the big room to be a sitting room, bedroom and dining room all in one go. It will feel like a large expensive modern house but without the heavy price tag.
The main seating backs onto the big step and faces the partition wall which neatly houses a huge 4K TV, and all the usual kit, beneath a roller tapestry. This prefabricated wall incorporates storage on the reverse side and integrates all the gear for home automation, security and communications.

To convert the living space into a dining room the table comes up from the floor – (see magic table on http://www.originaltwist.com)…… the TV disappears, the bed tips up and away and the sofa glides back into the recess behind it; fanciful maybe but it makes excellent use of the space and easily accommodates large dinner parties. The sofa mechanism is quite simple with the sofa parking on top of the cover door when it is deployed.
With all the clutter cleared away there is plenty of room for partying with the ‘bar height’ raised platform making a safe place to put food and drinks. This house really is an entertaining machine.
There is a doorway either side of the big screen; one for the upstairs loo and the other to the kitchen. The generally high ceilings allow for an optional extra bedroom over the upstairs kitchen, accessed by a stairway along the back wall. It has to be very light and airy looking to preserve the cube like look of the main structure.
The house is suited to be built on a sloping site so access to the first floor would come from that level and ideally via a glass entry vestibule to the front door on the wall opposite the big glass south wall.

Conservatory, kitchen, bedroom, car - what else do you need?

Conservatory, kitchen, bedroom, car – what else do you need?

Downstairs the large breakfast room enjoys a wrap around conservatory and incorporates a second small integrated kitchen. Doors to the rear lead to an en-suite bedroom, a loo and the garage.
The daily grind won’t seem so bad when you start with a cuppa in bed watching the morning news then a shower (in the small shower-room on the bed level) before going downstairs to a sunny breakfast before nipping through to take your Porsche off to work.

Of course the eco-technomologicalness will be state of the art. The 24 Sunerg hybrid solar panels actually dictate the size and shape of the roof and the red trim panels are fixed directly to the panels (PV and wet solar are all 2m x 1m).  4 of the panels on the steep roof will be wet to give a massive 8sqm to feed my own twin tank heat bank design – my speciality. The other 20 panels use micro-inverters to give a nominal 6kWp and a real 2-3kW in the winter to run the little air source heat pump which also does some neat heat recovery from the house and uses some ground heated air too.  Batteries make a huge UPS which, combined with the batteries in the electric car, largely makes the mains supply more like a backup.

Eco pod

Eco pod

At the moment this is just an exploratory sketch but with serious intent. Local councils are being encouraged to make space available for self build houses and after a bit of polishing this design might gain some followers. If this is too radical for you, have a look at the more acceptable Brexit house.

More on this topic in LIST OF POSTS

Air Source Heat Pumps vs. gas boilers

First the bad news for heat pumps. 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 a lot of which are claiming over 4 these days. So maybe heat pumps are intrinsically good but tricky to install?

Despite all that, 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. You can see this on the blue line on the graph. Delivering 35c water to the underfloor heating the COP goes over 5 as the outside air goes over 10c. Note that the pale blue line (delivery temperature 50c for radiators) still only goes to around 3 so for most of the time the average COP will only be near 2.5. So, heat pump with radiators – think carefully.

Gas per kW.hr costs about 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.
Perhaps the performance could be lifted further?

The next bit is a bit dull – you might want to skip on to conclusions below.

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.

A small ASHP can run a bit 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.

Of course, with PV panel prices falling relative to electricity prices, the time is coming when your heat pump will run for free while the sun shines. At the moment it looks like we are firmly in no brainer territory and it is certainly worth checking now to see how the sums stack up.

A tip to make your heat pump installation cheaper. Use the PV panels and an energy diverter (e.g. Eddi) to heat your existing immersion heater. then you won’t need the special tank to accompany the heat pump which will just do central heating. Your installation might get a lot nearer to the £5,000 grant.

And while we are at it, don’t forget to consider a mini-split heat pump air conditioner. It’s an air to air unit and relatively so cheap it’s hard not to go and get one right away. I did.

Like what you’ve read? Find more essential reading on my e-book

‘Dream House – Down To The Details’ here:-

More on this topic in LIST OF POSTS

Eco-house delivered in a day – cheap too.

Root2Eco-house delivered tomorrow morning and ready to live in by tea time? “Yes Sir, no problem, will that be the £130,000 ROOT2 or the ROOT2 MAXI for £170,000?” The smaller Root2 Eco-house comes in 3 towable modules that are parked in a ‘T’ shape with the gap in the middle covered by a hexagonal roof. The hexagonal living room under the roof is a spacious 4.5m wide and the fully glazed front side gives a modern airy feel to it. Each module is constructed in structurally insulated panels (SIPS) with smart double glazed PVC windows and doors. The roof, floor and end panels are wrapped in zinc to give a modern look and water proof durability. Being just 2.25m x 5.25m the modules can easily, and legally, be towed by most family cars. The ‘wet’ module goes in the middle of the ‘T’ and comes pre-fitted with a wood burning stove connected to a 475 litre heat bank which is also heated by wet solar panels (6sqm on the roof), an immersion heater and an lpg Vaillant Eco-plus gas boiler just in case. The wet module also houses a neat galley kitchen, a shower and chemical lavatory which can be exchanged for a normal one when a septic tank and soak-away is installed. Of course the wet modules wouldn’t be wet without water so a 1,000 litre tank is placed over the roof to give adequate supply and pressure. A trailer is available for fetching another 1,000 litres in an IBC if necessary. The other 2 modules together provide 2 small bedrooms, one double bedroom and an office – useful 50msq accommodation for a family of four. Under-floor heating is pre-installed throughout and quickly connected at the setting up stage along with wiring, made simple with Z-Wave wireless lighting and switching which also enables many functions to be controlled remotely on any i-pad or mobile phone. Root2 is a proper Eco-house with 42% of the build cost going into sustainable energy equipment. The other 2 modules at the sides have a total of 18 PV panels on their roofs to give a total of 4.5kW (kpa) and the power, stored in batteries, is handled by a Power-Router unit that also allows connection to the mains when available. While the Eco-kit incorporated might look a bit excessive at first it does allow the house to be placed very quickly on site in a fully working state and provides a most economical off grid user experience after that. The extraordinarily low price also comes without the need for expensive extras such as site preparation and various professional fees; a patch of land with permission for 3 caravans will probably suffice. Being a new house built by a contractor Root2 should qualify for the UK ‘Help to buy’ scheme and will enable many owners to enjoy comfortable living without a huge mortgage burden. No doubt some users might sell existing properties and release cash for holiday villas or ski chalets. Corporate purchasers will value the instant hassle free solution for housing workers on site with all the proper modern comforts of home. The ROOT2 MaxiThe maxi is built to the same concept but each module is 6m x 3m and the central hexagon is 5m wide. While ROOT2 is like a flat in size the Maxi is just like a house. ROOT2 Maxi is not towable and is delivered on a truck with a crane and in that respect can be installed almost as quickly. If you want a well appointed 5 bedroom Eco-house next week then this is the way to go.

Like what you’ve read? Find more essential reading on my e-book

‘Dream House – Down To The Details’ here:-


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.


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.