We’re getting an air source heat pump installed at the moment. It’s something that we’ve been thinking about doing for about a year now but when our ancient boiler finally died this spring we decided to make the leap to heating our home in a cleaner way.
The main thing that put me off doing it sooner was the vast amount of unknowns about what heating with a heat pump would actually mean in practice. So I want to use this as an opportunity to learn as I go and crucially pass on what I’ve learnt to others who are heat pump curious.
I want to know all the little things that matters day to day, like what it looks and sounds like, how you service it, and what the controls are like and how long it takes to get used to the different way of heating your home.
My information is UK-centric, but those of you outside of the UK may still get some benefit.
I’m not going to talk about how heat pumps work because there’s plenty of other advice about this online.
Aren’t heat pumps expensive?
Well, yes they are. Ours is going to cost about £12,000, but at time of install we get £5,000 up front in subsidies from the UK Government for not choosing another gas boiler. This is organised through our installer.
To look at it another way though. I work from home now, as I have a fully remote job I never go to an office. So the largest part of my carbon footprint is now heating my home. Previously my rail season ticket was about £3,300 a year (not including price increases), so two years of not travelling by train has paid for our heat pump.
What an indictment on the state of the British rail network…
Ground source heat pumps cost more, and need a big garden or space around the property to dig down into which we do not have. So I can only share my experience with an air to water heat pump.
What are the benefits?
I’m doing this to reduce my carbon footprint. The upgrade we’re going for makes more economic sense for someone not on mains gas.
We’ve been advised that our monthly energy costs should be comparable to our old gas boiler. Electricity usage is more expensive than gas in the UK, but the heat pump generates up to 3 times the energy for the amount of energy used to create it. So it should work out about the same, or slightly less than what we pay now. I used to work for two green energy companies and doing the maths, this checks out. It will be more expensive than quoted, but this is because the energy prices are going up so much generally.
Given the economics of the world too, I’m primarily also doing this to reduce my gas usage. It will reduce the local pollution in our area. Plus more electricity and a greener grid is key to energy independence.
Energy prices are only going to go up from here on in as prices in the UK are tied to the energy price cap which is due to go up this autumn, so it’s going to be harder for me to measure the financial benefits in the short term, but I’ll collect all the data I can.
Some stats about our home (pre heat pump)
How well a heat pump works is based on your home and things like its physical footprint, how big it is, the number of rooms you have and how much heat loss you have.
- Victorian semi-detached property with a small modern extension
- 3 bedrooms
- Energy rating D (with potential to be B)
- Powered by green energy supplier
- 6 radiators in the house
- Done all the easy insulation we can do, we have some insulated floors and split bedroom/attic roof insulation that needs upgrading
- No underfloor heating
- 75 square meters of floor space over three floors
- Our house has rising damp (which is common for something built around 1891). It’s been treated, but something we have to balance when improving insulation more
- We have a wood burner as backup heating, although this is used sparingly due to local pollution
- Our average electricity usage in a year is 2,861 kWh and our gas is 12,409 kWh
- Normally have our heating on from end of September to March, we don’t have our heating on overnight and have our thermostat at 19 degrees when we do.
What are the steps for getting started?
- Find an MCS accredited installer – this is important for making sure that the correct steps are followed for both assessing the suitability of your home and handling the commissioning and eligibility for the boiler upgrade scheme (which gives you £5,000 towards a heat pump, paid directly to your installer)
- Get a suitability assessment booked in, this is where representatives from your installer visit your home, measure your rooms and your radiators and look as your current plumbing and heating and complete a form that will form the basis for your quote. From this they’ll work out what capacity heat pump your home needs, and what if anything (such as radiators) need upgrading. They’ll need details from you like where your energy meters are, where your fuse box is, where your boiler is currently sited, where your cold water tanks are etc
- They’ll also measure the space where you intend to place your heat pump. For air source you need more space than you think – over a meter wide and two meters clear space in front. There can’t be anything blocking the air flow. We had a small wall that had to be removed for example. They’ll let you know about the feasible spots for your heat pump unit, and where your water tank should go – normally in the location where your boiler was
- You’ll also need a new Energy Performance Certificate (EPC) created. You may already have one if your home has any other green tech installed, or if it’s been put on the market in the past two years. Otherwise you’ll need a separate, independent assessor to come to your home to assess how your home is currently heated, what insulation you have, and what your likely heat loss is. An EPC is a requirement for proof of eligibility for the boiler upgrade scheme
- Both of these checks take about an hour each, and are organised through your chosen installer. It’ll cost about £150-£200 although many installers seem to deduct this from the overall bill if you do decide to go ahead
- Get a few different quotes and compare their advice and prices, ask lots of questions. It’s a lot of money to spend on something that’s still quite a new idea for a lot of people
- Once you have a quote, you should an an estimation of your energy costs/usage, and your expected stats, including your Coefficient of Performance (COP) and Seasonal Performance Factor (SPF). Basically how efficiently your system could work in your home at its best and at different times of the year
- Visit a heat pump – if you’ve not actually seen one, they’re rather like an outside air conditioning unit that works in reverse. I didn’t know anyone else with one, but it would be good to get an idea of their size and what they sound like. I didn’t have this option sadly.
What are some of the pitfalls?
- Don’t you need underfloor heating? Some homes might, but our small little victorian semi should be toasty enough with upgraded radiators
- Don’t you need to be fully insulated? Yes, but you should really be with gas as well and many homes are not. This is something we’ll have to improve more as we go
- It may take more time – depends on ow busy your installer is but in theory we could have gone from about a month from initial enquiry to install
- Prices for running a heat pump are going up but then the costs for heating are going up across the board. I’m hoping this will make our home more resilient to this in the longer term
- They people say don’t heat as well, this may be subjective, it uses slower ambient heat, either way I will be a good test subject because I run cold and really prefer warmer weather
- Refrigerant is needed for heating to work, but arguably has less impact and no air pollution fumes when compared to something like gas or oil
- Heat pumps are more hands on than gas, requiring you to monitor how it’s working, optimise and improve things as you go. I find this sort of thing fascinating, but others may not
- There are fewer people to service and help when things go wrong but this is something that should improve over time.
Heat pumps require some behaviour change
Heat pumps use ambient heat, which means setting the temperature for it to come on and leaving it on (even overnight) rather than boosting up the heating as and when you need it. The carbon cost is a lot lower than having the heating on and off as with gas, but that is going to take some getting used to. I’m so used to turning something off when it’s not needed, but that’s simply going to make the heat pump less efficient at what it does.
Some people say heat pumps don’t heat as well, but they heat your home different to something like oil and gas, you can’t boost the temperature up really quickly, and that leads people to say they’re not as warm, when it simply works differently, and takes some adjustment.
They make some noise outside so it’s worth having a chat to your neighbours about it, but this should only be an issue in the winter when it’s working harder. It’ll be quieter than the road at the back of our house at up to 35 decibels. I am looking forward to hearing this in the real world.
Our planned system
- Midea 8kw air source heat pump using R32 refrigerant
- 200L water cylinder (with immersion heater)
- All but one of our radiators are being upgraded, one is being reused in one of our smaller rooms
- Old boiler will be taken away and recycled, as will some of the old piping, and supply to boiler will be capped off (as we still have a gas hob to cook on)
- Coefficient of Performance (COP) estimated at 3.67 (average)
- Electricity usage total estimated at 4,605 kWh (heating and hot water)
- Installation will take about 5 days
What could I improve in the future?
This heat pump itself will last about 20 years, and I expect the costs will come down over time, a new unit will be much cheaper by the time we need one again, and the pipework, electrics and radiators will already be upgraded for this purpose by our initial install.
Heat pumps don’t improve your rating on your EPC rating as far as I can tell which seems a bit of an oversight, but clearly they do improve the energy impact of your home, so I hope this will be addressed.
There are no heat pump tariffs in the UK at the moment. Seems to me that we should be charging people less for electricity and more for gas due to its lower carbon cost. Some suppliers are trialing heat pump specific tariffs in the UK, and there are smart tariffs (which charge you less when there’s less strain on the grid). Reducing the unit rates for electricity or having cheaper rates to use in the summer would encourage more people to make the leap.
Retrofitting insulation – our EPC advises that we could improve our energy rating by at least one letter by looking at this. it’s on the list, but is potentially more expensive than the heat pump and more intrusive in terms of the work needed (scaffolding etc) and changes the outside appearance of our house. We have few cavity walls in our home, so this or internal insulation are our only options I believe.
We might consider putting some solar panels on the roof, but we don’t have a lot of feasible roof space that would make this viable, however it’s more of an appealing prospect with a heat pump (we’d use it primarily to heat water).
We will remove our gas hob in the future, as we’ll only be paying the standing charge for gas to cook with (we have an electric oven).
What happens during installation, and more pictures.