Heat Pump Experience

[DerekC]

I am interested in gathering practical experience with heat pumps. I can contribute mine.

Two years ago we replaced the six night storage heaters in our small village hall with an air source heat pump feeding low temperature radiators. It cost about £15K of which half came as a grant from our local council. The hot water for the kitchen and toilets is separate, with an instantaneous heater that only works when needed. The results in terms of energy saving are excellent. Our target was to halve the electricity consumption and that has been bettered, although the situation is confused a bit by the fact that the hall was closed during the pandemic winter of 20-21. Also the users love it because the hall temperature can be controlled to match usage and it can be warm in the evenings when the old storage heaters would run out of heat!

My reason for posting a thread is that I am wondering how that translates to your typical domestic property (e.g. my house). The hall was an ideal target in some ways - night storage heaters are all-electric and very hard to control, there was no existing piped system, we didn't need to worry about large demands for hot water etc etc. So how have people coped with converting an existing gas or oil-fired system, what did they do about hot water, etc etc?

I am much more interested in practical experience than opinion, however well informed. So if you have been there and done it and have something to share, please post.

 

[Snow1964]

We have installed two small-medium air heat pumps last Autumn (ideally could have had one bigger unit, but they need a 3 phase electrical supply and our house, like most is single phase). We mainly had them for whisper quiet air conditioning, but they also do heating, dehumidifying and air purification (pollen filters etc)

We also have underfloor heating instead of radiators which works off a 12 year old gas boiler and makes the house fairly toasty if you choose to crank it up. Our hot water is a tank heated from the boiler or an immersion heater.

When our boiler failed (when it was cold in November) and we were waiting parts we used the heat pumps for heating, they seem to work well but because the inside units are located on walls and are sited where it was easier to add the pipe work they produce a rather uneven temperature in the bigger rooms (bit like using a fan heater, which is effectively what they do). But we hadn’t really specified them for this job, ours was to provide cooler environment for being at home in summer.

Our thoughts are to eventually look to convert the gas boiler and put an inside unit (heat exchanger) in its place to run the underfloor heating. When we did the costings last summer we were basing our gas usage as nearer £700 per year, so decided not to replace the boiler for a while to save the extra installation outlay.

Obviously the price of gas has jumped, so ideally need to change much faster, but to get the best value from the heat pumps really need solar panels to get free electricity, coupled to a couple of battery storage devices (eg Tesla power wall) so you can warm the house in morning before sun rises in winter.

So yes it is a good way forward domestically, but only if you invest about £20,000 and get the solar panels and electricity storage as well. Once done should have virtually free heating forever going forward, and if you have enough solar panels free electricity to run your electric car as well.

But if you just try and do a cheap add on, (or do the conversion piecemeal) to a poorly insulated house then I would think it is a bad idea. It is a different form of heating where everywhere inside is a uniform ideal temperature, not like old heating systems with warm parts and cold parts so you need the external insulation to be good.

 

[najaB]

But if you just try and do a cheap add on to a poorly insulated house then I would think it is a bad idea.

As noted in another thread, insulation should be the number one priority for any homeowner. It doesn't matter how efficient your heating system is if it's trying to heat the outside environment!

 

[GusB]

My housing association installed an air-source pump as the final stage in a package of measures. They did the insulation (loft and cavity walls) first, replaced the double glazing and then installed a solar panel for the hot water. The solar panel alone resulted in a significant drop in energy consumption, but replacing the original storage and convector heaters made a huge difference.

It took a while to get used to the low-temperature radiators at first and it felt as if the house wasn't warming up at all; I'd previously lived in houses that had gas heating where the radiators got properly hot. I've since adjusted the radiator water temperature setting at the boiler and it seems much better now.

I dread to think what my bills would be like now if the original economy 7 / storage heater system was still in place!