Air Source Heat Pumps any good?

5 Sep 2012
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United Kingdom
Hi guys,
It's been suggested we could be eligible for some energy efficiency improvements, including an air source heat pump heating/water system.
We live in an old draughty house and they're suggesting to also internally insulate the solid stone walls, increase the loft insulation and fit solar panels to feed the ASHP. I’ve read that heat source systems aren't very good in draughty houses… any thoughts?
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Solar panels to feed ASHP.

Hum, probably no or little sun when you need your ASHP
That’s the type of feedback I’m looking for, positive or negative. It seems they’ve been used in Scandinavian countries for decades tho (unless they’re ground source?).
I remember the winter of discontent and how cold I got with no heating as even with gas, still needed electric to run, so since then all homes have had either a gas or open fire for emergencies, and also an electric oil filled radiator.

Today I have 6 kW of solar panels, and a 3.2 kW battery, so with a power cut I stand a chance of keeping the central heating running, however today this 1707410922331.png is my solar PV, and 485 Watt will not even keep back ground stuff running, never mind a heat pump. Here is total 1707411063574.png for the day, yesterday was good day for solar, it peaked far higher 1707411194429.png but still unlikely to power a heat pump for long. My battery will charge at 2 kW and discharge at 3 kW this is enough to span the peaks and troughs, but to store on good days and use on poor it would need to be 10 times that size, the idea is once a battery and solar are fitted, one can buy electric at a cheaper rate over night, so the battery can be topped up over night, and you can export during the day, so battery does not really need to be that big, it is a tick the box exercise.

The heat pump works better the less the differential is, so the radiators need to be larger for it to gain the maximum, and most homes have a 60 amp supply, it can go up to 100 amp, but my 19 kW oil boiler is over 80 amp at 230 volt, what we hope is as more efficient it does not need 19 kW may be a 1/3 of that, so 27 amp, however most the heat pumps are well below that.

However with gas or oil we can reduce the energy used by turning of the heating when not required, and by having a boiler over the size required to maintain the home, we can allow the home to cool while not being occupied, then reheat room by room as required, to maintain my house likely only requires half the size of boiler, so could maintain it with 14 amp, but then we are wasting power by heating rooms not occupied as we don't have the power to reheat them, only maintain them.

So step one must be to insulate the home, and reduce losses to a minimum, and once that is done the heat pump can maintain the home better. The gas, oil, solid fuel would also heat it for less money, so what you are looking at is the time the home is not heated, and how much the temperature drops during that time.

So over night my heating goes off at 15 minutes past midnight and comes on again at 8 am, the TRV in the living room actually records the temperature as a graph, so I have this 1707412770978.png report, it was 11 am before the room had recovered, and one can see it cooled to around 15ºC. And one can also see how the hotter it was, the quicker the temperature decayed. So even if you only drop the temperature by a few degrees, you can save a lot of energy, I am not an early riser, so 11 am for me is fine. But using a heat pump it would double the recovery time so 2 pm before recovered, that is simply too long. However if I reduced losses by half then it would be a faster recovery, but so would the oil fired boiler, so could set it to start at 9:30 am instead of 8 am so I would save even more.

So what I am saying replace the 19 kW boiler with a 27 amp heat pump it may work, but what is being done, is the promotion sites are not comparing like with like, so for a retired couple it is possible the heat pump would work, however before I retired I did not want the house warm until 6 pm, and by 10:30 considering going to bed, so only want house warm for 4½ hours in every 24 hours, keeping the home warm for 19½ hours when not required because the heat pump is not big enough to reheat the home, is clearly not going to work.

So what we want is larger radiators (output wise, which is not the same as physical size) and a large boiler to quickly recover the home temperature within the time geofencing will have when it detects your returning home, at least for rooms you will use on arrival, so looking at ½ hour to reheat home, only way to do that is with fan assisted radiators, and when you look at it this is where the heat pump really comes into its own, as with fan assisted radiators it can both heat and cool the room, and if we are heading for globule warming we will need to cool the rooms in summer, so now we are talking, however two stumbling blocks, one is cost, the other is most heat pumps being installed will only heat the home, rather a blinked approach, seems governments don't really believe in globule warming or we would be fitting the reversible type, so it is just a way to generate jobs and get people to spend more money. It has nothing to do with globule warming or the pumps would be reversible.
I seriously doubt that any legitimate company would be offering an ASHP installation and extensive new insulation for free. This sounds a bit like a scam to me.
If such a deal is available I am sure that many people would like to take advantage of it. I also have serious doubts that anyone is giving away tens of thousands of pounds of heat pumps, solar panels and insulation for nothing. Why would they?
Hi guys,
It's been suggested we could be eligible for some energy efficiency improvements, including an air source heat pump heating/water system.
We live in an old draughty house and they're suggesting to also internally insulate the solid stone walls, increase the loft insulation and fit solar panels to feed the ASHP. I’ve read that heat source systems aren't very good in draughty houses… any thoughts?

The big problem in the U.K. is the industry is in its infancy and it’s often installed based on bad advice or wrongly designed system.

have a look at some heat geeks videos, they are very informative.

If you are really interested in a heat pump, spend and awful lot of time doing your research, find a real expert, not a salesman to find out if it will work

I’ve read that heat source systems aren't very good in draughty houses
No heating system is very good in an old draughty house.
They will all cost far more to run than they should regardless of whether they are powered by electricity, oil, gas, coal or anything else.

Heat pumps do work and are valid - provided they are specified and installed properly.
If not, then they will cost a fortune and heat very little - as will any other badly installed system.
If their chapping doors offering it for free then its normally a scam or a company set up to squeeze the life out of govt funding (i.e. not giving a $hit if any of it works, just slinging it in to claim the grant money and there gone)

Heat pumps work fine in old houses, its a source of heat, as long as the heat it puts in the house matches the heat leaving then you can heat your house with anything.

However... It does take a company that want to do a good job. They have to calculate heat loss properly, work out rad sizes, pipe sizes and controls to get the best out it. As where a boiler just slung in to an existing system will work (not efficiently, but it wont cost silly money to run) a heat pump running of electricity at the prices we have can cost a lot (an awful lot) if its done wrong. Although if its done right it can run cheaper than a boiler.

Solar PV is a great addition to them. Of course PV output tanks in winter when you use the most electricity in the heat pump, however spring/autum can be nearly free day time heating and free hot water all summer (again if done smart) so over the year on a good system this will significantly reduce costs. (you cant get natural gas panels on the roof to supplement a boiler!)

Insulation will help with any heating system, for some reason there is a general chant of you cant heat an uninsulated house with a heat pump, reffer to my 2nd paragraph. However, if you plan to insulate at some point its far better to do it first and that way a heat pump can be sized for the lower heat loss, rather than one sized for a higher heat loss, as oversizing a heat pump will cause its own problems. And the lower temperature it can pump to the radiators the more efficient it becomes, so insulation means the radiators can be run at lower temperatures. You can do this without insulation, but the radiators can end up being very big and unsightly in older properties.

All in, they work great, the technology is fine, the installer base is not. There are some amazing installers doing great things for their customers, but there are also a lot of uneducated folk jumping on bandwagons seeing pound signs in govt funded money. And its the design of the system that makes or breaks it with heat pumps.

BUS scheme give £7500 towards eligible homes for a heat pump. the work your talking about sounds closer to £20-30k so id have a big pinch of salt with it.
Thank you all for taking the time to reply.

I take all your points on board, and agree getting it all for free sounds suspicious. The funding would be from the Scottish Government's ECO4 scheme. "Claim up to £50k in govt funding towards free home energy efficient upgrades". Apparently our EPC rating of G would qualify us, although we'd also need to meet other personal criteria.

The sales guy suggests solar panels, increase loft insulation, internal insulation to solid stone walls on old half of house, cavity wall insulation to the more modern half of house, ASHP system, perhaps insulate over the large flat roof depending on what insulation is there… but said they couldn't do underfloor insulation.

So even if the ASHP turned out to be unsuitable (or too expensive to run), would it be worth it for the £tens of thousands of free stuff, then I pay to get a gas boiler fitted later?
If you want to take advantage of the scheme - start with the scheme, do some homework, then start scouting around for installers who've done a good job.
Not the other way round.

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