Next steps with home renovation, heat pump?

220 Posts


So we are planning to have an extension built and would like underfloor heating as an alternative to radiators. We currently have a 5 year old boiler that my plumber says will be capable of running the newly proposed underfloor wet heating but I am considering the next few years and overhauling the whole system with a heat pump to heat the water instead of the boiler but could I replace the boiler and just have a heat pump do everything including hot water? We have no water tank currently as we have a combi boiler but as we are renovating it seems an ideal time to get it all done in one go, otherwise if we decide to do something later we might have to reconfigure pipes etc which won't be the easiest of job.
Secondarily we currently have solar PV for electric generation and don't store our generated power, have not plans for an electric car and don't use it to heat water, so could the excess be used in conjunction with the heat pump to make more efficient use of what is being generated.
Then there is a question of a/c, with the climate warming up I would like to consider putting air conditioning into the bedrooms (x4) of the house, would an air source heat pump be able to do this as well?
Anyone know of a recommended product to do this or set of products or has a working system that does this? Looking for ideas of cost.
If this is a big vague let me know what other details are needed, not particularly looking at payback at this stage more interested in what solutions are available and anyones recommendations based on experience.
Thanks
Secondarily we currently have solar PV for electric generation and don't store our generated power, have not plans for an electric car and don't use it to heat water, so could the excess be used in conjunction with the heat pump to make more efficient use of what is being generated.
Then there is a question of a/c, with the climate warming up I would like to consider putting air conditioning into the bedrooms (x4) of the house, would an air source heat pump be able to do this as well?
Anyone know of a recommended product to do this or set of products or has a working system that does this? Looking for ideas of cost.
If this is a big vague let me know what other details are needed, not particularly looking at payback at this stage more interested in what solutions are available and anyones recommendations based on experience.
Thanks
0
Latest MSE News and Guides
Replies
To achieve maximum efficiency you've got to revamp the whole heating system to run at low flow temperatures (35-40 degrees) so the costs are quite high. You will get some back in the way of the Renewable Heat Incentive but it's not a Kings ransom (I'll get about £5k back over 7 years for mine). You'll need a hot water tank as heatpumps don't work like conventional boilers and you need to operate them properly to maximise their benefits.
As far as I can determine the biggest problems that people have with heatpumps is that they tend to be under specified, bunged onto existing systems, not planned properly and most of all not used correctly so you really do need to do a lot of research to understand what you need and what you want to achieve
Generally you need most of your heat in the winter when the days are long, the sun doesn't shine and their efficiency is at their lowest so I don't see that they match the energy provision of solar panels which produce most in the summer and least in the winter. The government stopped the FIT scheme for solar energy a year or so back so the only options you have are to try and use all you can or try and sell some back to one of the energy companies (you need to find out who is giving the best deal and for how long)
You can get reversible heatpumps which heat and cool, likewise you can get fan-coil units which will either heat or cool and blow the air about or even a split aircon system with multiple air units.
There are a lot of options, all of which are likely to be quite expensive so you really do have to do a lot of very careful sums to decide whether the cost and benefit is worth it all.
We refurbed our bungalow 10 years ago and decided at the outset to put u/f heating all over and install a heat pump and we reckon it's probably paid for it'self in terms of lower energy bills and the RHI. BUT - we don't have access to mains gas, so the alterniatives were LPG, OIL, Biomass or replace the storage heaters. Had gas been available then the heatpump wouldn't have been even considered. It does provide our hot water quite cheaply in the summer but I'd still be tempted to put in gas if they did decide to run it up our road (highly unlikely as we live a long way from the nearest gas main and we've got a river between us and it)
1. 60sqm of underfloor heating going in the extension, so my current gas boiler can manage this alongside the other heating requirements.
2.Like to add a/c at some point.
3.Like to make better use of solar generated and not used.
I have been looking at the LG therma range and it looks like it can do the heating and the cooling, so I think it could cover all of the bases, but I could retro fit a heatpump and take out my boiler at a later date, so no rush, just annoys me that I'm wasting the generated electricity, being on FIT and an assumed 50% export then it's money down the drain.
https://www.lg.com/gr/download/resources/CT32004443/CT32004443_1641.pdf
Was alternatively thinking could get a hot water tank and use that to feed the combi, so divert the solar to heat that when there is generation available and heat the water up so the combi might not need to kick in for some of the day/morning showers, then could swap out the combi later with a heat pump once they come down a bit more in money. But having said that the ones above are around £3.5k starting price, plus install. Batteries are still beyond the sensible in terms of using them to store what is generated due to price, so hot water tank seems to be most sensible option.
Other point is that if I can get one device that does it all it saves buying a separate a/c system.
I really dont know how much you spend on say just hot water but in my case with a heatpump it's around 20p a day at this time of the year, posssibly 30-35p a day in the winter which is around £100 a year. Say you spend twice that because you might be more profligate with your hot water, it's still going to take you a really long time 6000/200 = 30 years to recover the cost and if you dont get enough solar energy to cover 100% then you'll have to supplement it from the grid and as i said in my previous post, even heatpump leccy costs more than mains gas
I did explore solar thermal when I installed my heatpump but the installer pointed out that the £1500 cost would take 15 years to pay back if I was only spending £100 a year or less on heating water anyway
Even just installing a tank with all the associated plumbing and a solar diverter to recover 50% of your generated capacity will probably take 3-5 years to recover the cost. I know it may be great to be green but can you really afford it because it's can have a really long term payback period and you don't know whats going to happen between now and then.
In the end it's your choice and it might give you a fuzzy warm feeling to go a bit greener but don't think that all these magic devices are going to save you money especially in the short term.