Air source heat pumps

[bluebellbow]

We are self building our new house and as such cannot put in a gas boiler due to government rules on new builds. As I understand it our options are air source heat pump, ground source heat pump and biomass boiler. Husband wants to opt for air source heat pump. I’m just looking for an idea of running costs please? The house will have five bedrooms all ensuite. From the little I’ve read so far, we can apparently apply for a grant towards costs (which look to be £25k plus) as we are self building? Has anyone managed to go this? It sounds like it’s most efficient to do it with wet underfloor heating, does anyone have this set up? Does anyone know what equipment you have to accommodate in the house for this system, from what I read it seems like it’s the actual pump unit outside, then inside just the water cylinder needed and obviously the stuff for the underfloor heating under the floor? I will have a cupboard downstairs the size of a standard airing cupboard basically- will this be ok to house the cylinder? Thanks for any advice, we are wary of making costly mistakes as we know nothing about it! Also if anyone can recommend any companies in the south east you’ve used who install these systems… thanks

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Updated by MNHQ
Landed on this page in search of heat pump advice? Find our guide to installing a heat pump in your UK home here. HTH!

Because it is a lot more expensive in terms of system cost for a system that would hardly be used anyway if the insulation is of a high standard ?

So why look at biomass then? They are really expensive and need feeding! Most people don’t build to passiv haus standards. You also need hot water! There’s not a no cost option. Lots of things use power, not just heating. Having a warm house doesn’t charge your car. Starting with a brand new house offers options but we are not going back to fossil fuels any time soon.

You sell the biomass and swap it for gas. Both will give you hot water. You could also have an unvented tank with either. And the whole exercise would be a lot cheaper than ASHP, for a system you would hardly use anyway because of the insulation.

I don’t accept the “hardly use” concept. Building to those standards is difficult!

Not really. But if you have massive glass walls it probably is.

I have a lovely garden and woods beyond. I absolutely love seeing the garden and wildlife and changing seasons. It was a conscious decision to have glass and not live in a hermetically sealed box.

Batteries have a certain life in the number of charge/discharge cycles they will perform, at a certain capacity. Normally 60%-80% of rated capacity. Multiply these numbers together to get the whole life capacity. Now divide the the cost of the battery by this number to find the cost per unit of using the battery. On current prices the number is very close to std rate electricity, and more than some of the newer smart tariffs.

We have a reasonably sized solar array ( 5kW 20+ panels) and in December we exported 1.85khr. If I'm very generous and say storing it in batteries would save 20p per kWhr, that is a total saving of 37p. A £10,000+ battery will take along time to payback at that rate. Equally, our total solar generation in December was about 50kWhr. 50kWhr is about 1-1.5 days of heating an average house in winter. If all of this was used for heating it would have knocked £10 off the heating bill. So as I said, batteries don't make sense, and solar PV for winter heating doesn't make sense. Insulation does make sense, and we only put the heating on half a dozen times this winter.

As others have said, you still need to heat your water, and an ASHP is the best of the options available

We have glass walls, but in the same way as it insulation, it was bought on performance of the glass and frames, not on lowest cost.....

Well same here but they aren’t as good as insulated walls!

Only relevant if you are only interested in the insulation not the whole system performance true. You trade the extra loss on cold cloudy days where more heating is needed, against the solar gain if there is any sun and no heating is needed. It only takes an hour of sun to warm our house through even if it is well below outside. So the insulation may be worse, but thermal performance is matched

Is it actually worth installing an ASHP though just to heat hot water and the few times a year you need to heat the house ?

What would be the payback time over standard electric heating (immersion heater plus wall panels) factoring in the cost of servicing on the ASHP as well ?

Edit, actually I think I can figure it out. My guess is hot water woudl be around £2 a day with electric, or 70p a day with a heatpump.

So you would save maybe £500 a year with heat pump hot water over electric resistive.

So if the heat pump cost £5K more than the electric you would be looking at a 10 year payback time. That doesn't include stuff like servicing either. Doesn't look great to me.

Sorry didn’t mean to offend anyone by saying airsource heat isn’t good, I’ve trawled though lots of comments from people who have them on different sites

Sorry pressed submit by accident. I’ve trawled through a lot of stuff online about it and a large percentage of what I’ve read is negative and makes it sound like an expensive minefield and quite difficult to manage and get the balance right. But I am not speaking from personal experience so I do appreciate all your replies. I’m glad it works out well for those of you who have it. I found out today that the government is delaying these new regs years now, so that is good news for us personally.

We have an Ashp and a five bedroom
house, running costs is difficult to quantify because we partly power it with solar, which means in June and July we pay almost nothing (for hot water as no heat that time of year obvs). But we def pay less overall than we did with a gas boiler

however I can confirm that it is currently WARM. My mother who is a heating freak has commented several times that it’s too warm for her.

the tricky thing is to get an installer who understands heat loss calculations and radiators etc. I got a great recommendation on here. We had to replace most of our radiators but no regrets two years on.

@bluebellbow No offence taken. However many users have totally unsuitable houses, expect water at 90 degrees and have under sized radiators. If you talk to someone where the set up is up is correct, it’s fine. I do find the expectations of some people are just too high and they don’t spend the money getting the house insulated etc.

You find all sorts of negative reviews because of a lot of things aren't easy to get right. Many are not specced properly. Many people don't understand how it works or how to get the most out of it. We had fab installers and took the time to really learn about it. I much prefer the kind of constant lower heat you get from an ashp rather than blasts morning and evening from red hot radiators. Also you get much more out of one of you have one or more of the following: solar panels, underfloor heating, battery, and MVHR. We have 3/4 of these so it works well within our system. So many ashps are not designed properly or as you say the house hasn't been prepared ready for it, so the heat doesn't stay in the house. I think it's especially bad in new builds when people don't understand how it works, never decided to get one and then haven't been told how to make it work for them. So much is user error that you can't just believe the Internet, or indeed anything published by The Telegraph who were literally paid to write bad news stories about ashps.

I personally would look at the numbers involved in putting in standard electric heating and solar panels. You may find that for the same budget you end up with a system which requires less maintenance and will give you free electricity when the heating is not required.

What do you mean by "standard electric heating" @CatherinedeBourgh ?

There’s no ban on gas boilers, and the current building regs still allow for them. The next update to regs (due at some point this year) will make them harder to install.

I had a biomass boiler and have recently switched to ASHP and solar PV. The biomass is a headache - they are really best suited to farms and environments there a lot of buildings with heating and you can automate the loading of the pellets etc. it’s a bit like diesel cars - they are considered old tech now.

i can’t comment too much on running costs for the new system as it’s only weeks old. It’s also been very cold. Currently tho I’m spending about as much each day as I did on pellets for the boiler and electric for everything else.

Using an immersion to heat the water for space heating and hot water powered by grid will cost a fortune. I know because I had to do this whenever the biomass boiler failed.
It’s having a kettle on all day (in effect) where as the ASHP heats at a greater efficiency. In summer, when the PV is in full flow and we only need hot water for showers, the immersion will work for free (plus we’ll loose less heat from the tank etc).

As others have said, spec the house with the best insulation you can afford - to reduce energy demand. Then get a ASHP appropriately sized, and Solar PV. Run a heap pump tariff and export your excess generation to the grid in summer. Easy!

You can have underfloor heating with electric coils, infrared underfloor or panels, or electric radiators.

It is the standard way of heating homes in much of France and Switzerland.

Those may be cheaper initially but they're just using a 1:1 ratio of electricity in and electricity usage. Ashps are multipliers of energy, our coefficient is generally at least 3,sometimes as much as 5 meaning the electricity in from the grid or solar is multiplied 3-5 from using the energy generated by the air the ashp sucks in. They are more expensive initially but the ongoing costs will be much less.

I would insulate as much as you can afford
Depending on where you live in the uk- solar panels/ battery could be a waste of time and money.
Think about it. Most of your energy spend is during the winter to heat space. This is when the sun is not shining. Yes during the summer your electric spend would be very low if not negative. But does that deficit out way the winter electric spend plus the cost of PV panels and battery? it does not. The batteries are very expensive £10k plus. You are not storing electricity from summer to winter. ASHP - cost 1 kWh per 4 kWh out. Best way to heat a well insulated home.
But really I think for most home PV panels are a waste of money. Better to source your electricity from renewable energy company like Octopus.

That's why I said run the numbers, it all depends on the relative costs of everything.

Don't forget to include the servicing and depreciation on a heat pump though, it adds to the cost.

I'm ripping out my heat pump because for the cost of replacing it with a new one I can put in more than enough panels to meet all our needs. It's also noisy and annoying.

My brother has a small ASHP in his shed.

It seems to work, BUT its a 'warm air' system

Given that heat pumps produce 'low temperature' heat what are the options for warm air heating rather than wet based systems?

North America seems to use these

Could you put alot of solar panels in the roof spaces, years ago there was a listed church in Islington that had the slate roof with the solar mechanism in them. Also woukd a couple/few of 8kw wind turbines on the wall or roof help gather more electricity.

We had a friend who fug up his garden and fit the cost of £16,000 put a load of pipe in the garden, which was connected to a converter and connected in the house, and it always felt cold without additional heating.

I’m very interested in this topic, we had a “man on windmill” caravan charger into a car battery in the 70s, and he worked hard charging the battery for a black and white tv(65watts), the belling electric fire(250watts) a small tower slow cooker (35watts) recharging batteries, my hairdryer (350watts), the iron(650watts) would kill it in about 15minutes, perhaps tif the inverter was bigger or the car battery was bigger…and sorry to be so Sheldon Cooper about it but it was a big thing for my mum and I.

I think this is how electric cars should be charged - free, I think heating your home should be “free”. It’s a big outlay in the beginning, so if it can be electric it should be free.

please let us know what you decide.