Air Source Heat Pumps and All That Jazz.

Am I being tempted? Well, yes and no.

Both the UK and Welsh Governments are investing a lot of money (an understatement- £12.9 billion, at least¹) in home heating and insulation. My good friend Jim, he of organic gardening fame who I’ve mentioned before, has just taken possession of 10 by 400 watt Samsung solar panels plus inverter to hook them up to the grid, a Samsung Air Source Heat Pump (ASHP) and associated tank, plumbing and radiators plus extra insulation in his attic, all for nothing, for free, gratis! Wonderful! Nice one UK and Cymric Governments!

above: ASHP designed to run continuously. Don’t stand too close in winter.

Sounds like a great deal, I know but there is a “But”....Currently, with winter here, short day length and often overcast, Jim's new solar production is nowhere near to keeping up with the ASHP's thirst for electricity. He's making a careful note to see whether the electricity he is hoping to generate during the summer will actually cover the running costs of the ASHP in the winter. The current (2024) price cap for electricity is 28.6p per kilowatt but selling your electricity back to a power company will get you as little 1.5p to 12p per Kwh...He's a bit worried.

ASHPs are best run continuously, they use pumps and fans to draw in air and expel it once the heat is extracted. Interestingly, this got a mention on Radio 4's Gardener's Question Time (Friday 6^th January). The air coming out of the ASHP is noticeably cooler than that going in and one of the panellists on the programme said that if the temperature was say minus 3, then the air coming out could be down to minus 6. From the programme's viewpoint this meant being careful what you planted near your ASHP but its interesting to consider what effect a row of houses running ASHPs would have- a new localised frost pocket?

Obviously with my “the problem is the solution” permaculture designer's hat on this might be turned to advantage by using making use of this cooing effect, possibly replacing a freezer. Incidentally, apparently a good ASHP can be run “backwards” to act as an air conditioner in the summer.

However, to get back to the point, ASHPs have been touted as the answer to home heating in the UK (and elsewhere) but Jim's concerns about power usage drove me to have a deeper look. The results, I think, are pretty worrying. A quick search online shows the power demands of ASHPs varying from 0.8 Kwh to 5.1 Kwh². Annual figures vary from 400Kwh to over 22,000 Kwh with a typical set-up using 5,475 Kwh per year.

This might be all very well if the power is met by the equivalent output from solar panels, as Jim is hoping but it turns out that this depends on the suppliers of the free kit. Jim's installer told him that they only fit quality products such as the £4000 Samsung ASHP, rather than the cheaper alternatives at only £1000 which are known to be less reliable.

They also only fit an ASHP if they can get 10 solar panels on the roof, otherwise they believe it will cost the occupier more to heat their home than a gas fired boiler (running costs can be up to 50% higher). Jim doesn't have a good roof for panels so hiss had to go on the ground on fibreglass bases which raise them at a low angle, OK for the summer but hopeless in the winter. Jim loses the sun form November to February anyway and has now lost half his garden to the solar panels as well... His supplier/installer does sound very scrupulous though as they returned to fit some extra panels for his neighbour who had taken up the same deal but only had room on the roof for six and once up, she panicked at her electricity usage, so they put another six on the ground in her garden.

However, not all installers are so scrupulous, as we should have learned from the earlier, often useless, UK government funded home insulation scheme- unscrupulous fitters simply threw the packs of insulation into lofts, often without even opening them, especially when the occupiers looked like they were unlikely ever to go up the loft ladder…

Similarly, in this current scheme, some installers are simply fitting ASHPs, often the cheaper, less reliable makes, without any solar panels, meaning that some occupiers will simply be unable to afford to run them, or will only be able to run them now and then. This will cause other problems as the start-up demand for an ASHP can be anything between 2.4Kw up to 15.3 Kw- more on this later.

above: no, not an alien robot or transformer but the other bit of the ASHP. Looks very simple and straightforward to me. Where’s my tap spanner got to?

Interestingly, last year I was cold-called by three different installers with very different offers, ranging from just some more insulation (50 mm of Multi Density Fibreboard or MDF on the inside of our bits of stone wall), just solar panels and a third offer, from the same folk who did Jim's, of 10 x 400watt panels, ASHP, water tank, plumbing and radiators, more insulation (difficult to know where it could go in our place) and, when I told them I was off-grid, a house battery. So yes, in some ways very tempting.

Here are the “But”s. Insulation first. 50mm of MDF goes on the inside of a stone, brick or block wall, usually on battens. There is a “dew point” in all walls; warm, moist air moves outward, through any wall, driven by the temperature gradient across the wall- warm on the inside, colder on the outside. As the warm air moves through the wall and cools, the moisture in the air will condense. The point in the wall at which the moisture condenses is known as the dew point. The wall here will be damp.

If we insulate on the outside of the wall, with, say, timber cladding on battens fixed to the wall, the dew point moves outward, often to the external surface of the wall, where, as long as the cladding is ventilated, it can evaporate off. If we insulate on the inside of the wall, with say MDF fixed to battens, the dew point moves inwards and, in worst case scenarios, damp and mould will form on the internal surface of the wall, behind the insulation. An additional minor point is that insulating on the inside of the walls makes your rooms smaller.

Back to the solar panels and ASHP. I would be in the same situation as Jim in that during the winter, when we really want the ASHP to be running, there will not be enough solar power to run it, let alone charge a house battery. We've currently got 1Kw of solar and during storms Isha and Jocelyn, with skies overcast and short day lengths, we produced just enough solar to cover using about 30 or so watts of LED lighting, a 10 watt router and charge a laptop and that's about it if we want to preserve the batteries

So if we took up the offer, the ASHP would stand idle pretty much throughout the colder months when it should be most useful and any overcast days with heavy rain (and winters are getting wetter- I'll be doing a piece here on my rainfall data which has built up over several decades now). On top of that, turning the ASHP on will put a severe load on a house battery which would then need more solar to recharge.

It looks to me that only people who have got decent incomes are actually going to be able to afford to run these ASHP continuously throughout the winter. For those who can only afford to run them now and then, consider the additional load on the National Grid turning on a million or so ASHPs is going to generate. Plus of course the even greater surge demand of plugging in a few million electric cars in the future. This is starting to look very dodgy indeed.

Jim's ASHP also requires servicing every year, currently at just over £100 per service, though whether there are enough experts trained to do the work is another matter. The BBC website says there are currently only 3,000 heat pump engineers registered in the UK compared to 130,000 gas heating engineers.

ASHPs are complicated things and not easy to maintain or repair. When they first turned Jim's new system on, nothing happened and it took another three visits from three different “experts” before it finally came on line. In terms of output he is well please- a gentle heat throughout his house, which is nice.

However, there's also the concern about blackouts and power cuts, as we have seen with the latest storms, when several thousands of homes were left without power and of course given global warming we can expect more rainfall, hence overcast days in winter and more, bigger storms. Power cuts mean no ASHPs so no heating and without a grid connection all those millions of solar panels just sit there looking shiny but doing nothing; Jim will be back to lighting his woodburner.

above: roll out them solar panels! But with a lifespan of maybe twenty years, better start wondering what to do with them all when they’re due for replacement, before its too late. Oh, it is too late…

A final point is that at present there is as yet no established industry for recycling solar panels. With a lifespan of about twenty years (and efficiency begins to tail off before then) the first wave of solar panels are coming down off roofs and new ones going up to replace them. Consider how many millions upon millions of panels are going up world wide. What are we going to do with all the old ones? Check out this BBC news story for more details.

Its fairly easy to see what's going on here. For a start the power companies are going to be laughing all the way to the bank as folk spend more money on energy for their electric cars and running their ASHPs. Then the power companies get to buy the electricity folk generate at greatly reduced prices compared to what they charge.

Samsung and other manufacturers of solar panels and ASHPs will be paid very large amounts by the governments for their kit, as will the installers and various surveyors who check it all out before and after the installation. All good for GDP and our capitalist economy. So although the UK government is pouring money into this, it’s actually subsidising a limited number of businesses.

To be honest, it all smacks of attempting to get out of the disaster that is Global Warming by clinging on to the same mind set and tactics that got us into this mess in the first place, that is, a blind, thoughtless capitalism and an adherence to a believe in technical solutions- so business as usual, no need to change our habits, lifestyles or attitudes.

Its easy for even low impact folk to fall back into this thinking trap; one of my responses to all the ASHP Jazz was, well, what I really need is a decent, small water turbine as that is where the power is here in winter. And I recently read an article for electrically heated wallpaper. Aaargh! Where will it end?

We may have to face up to the fact that if we don't get this sorted out in a sensible, genuinely sustainable way, we could end up with all these options being swept off the table, by Storm Apocalyptic or something similarly horrendous.

So am I tempted? No, I'm just a bit more worried than I was before.

Thanks for reading. Comments welcome, particularly your own experiences. Got a heat pump? Getting one? Here’s your space to let me know.

Next up, back to Konsk and the Great Takeover of the Place. Can’t leave you on that cliff hanger for ever! Till then, hwyl! Chris.

1. Its very difficult to find out exactly how much the UK and Welsh Governments are spending as there are so many overlapping schemes, old schemes being replaced with new ones and the like. Some of the earlier schemes have been near complete failures and the BBC have regularly reported on this, as here.

2. A Kwh or Kilowatt Hour is the amount of electricity used in one hour of operation; 1 Kilowatt equals 1000 watts.