‘I don’t regret my heat pump – here’s why you should get one, too’

Heat pumps have copped some bad press recently, and it’s time to redress the balance. 

I installed one in early 2022, and I love it. It is quiet, economical to run and keeps the house toasty. In my experience, there is nothing not to like. 

It’s true that getting one installed does present some hurdles. The technology is still unfamiliar in Britain – where annual sales trail far behind those in Italy or Poland – and there aren’t yet enough qualified installers. 

But make no mistake; heat pumps are here to stay. The Government has finally admitted that hydrogen will play no significant part in home heating, having scrapped two proposed hydrogen pilot projects, and it is preparing to ban “hydrogen ready” gas boilers in new-build properties from 2025. 

That makes heat pumps the default technology for a lower carbon future, and if Labour wins power at the next election it plans to continue the heat pump rollout. 

So everyone will need to get their heads around heat pumps soon enough. But if you’re thinking of having one installed right now, you’ll need to do a bit more research than you would to simply replace a combi boiler. 

I had the advantage that I write about clean energy policy for a living and could tap professional contacts for advice. But it’s not that hard, I have no regrets and here are 12 things I’ve learned. 

You could get a heat pump for free 

When I installed my heat pump it cost £11,500, of which the Domestic Renewable Heat Incentive (RHI) will pay back about £9,250 over seven years. The RHI has since been replaced by the Boiler Upgrade Scheme, which pays a lump sum to the installer. 

For all his backsliding on net zero, Rishi Sunak has at least raised the heat pump subsidy to £7,500, and in some homes that would cover the entire installation cost. Octopus recently installed the first heat pump for which the customer paid nothing.

Heat pumps can be cheap to run 

In the year to March 2023, my first with a heat pump, the total energy bill came to £1,600 for a three-bed terraced house.

That was the year when the Ofgem cap rose to £4,300, and the average household paid around £2,500 net of the Government’s emergency support schemes. 

In the year to December 2023, with all those schemes wound up, the results aren’t quite so good – I paid about £150 more than the Ofgem cap. As for the future, it’s a good bet that electricity prices will fall relative to gas as the proportion of cheap wind power keeps rising in the electricity mix. 

You may not need to install more insulation 

The one thing everybody thinks they know about heat pumps is that you can’t have one until you have super-insulated your home. But this may not apply to you. 

The Climate Change Committee has long claimed that 10 million homes are already well-enough insulated. And now even the Government – which for years has emphasised the need for insulation while refusing to subsidise it except for the fuel-poor – has changed its position. 

In evidence to a parliamentary committee last year it said that “around 90pc of homes in Great Britain have sufficient insulation measures to support low temperature heat pumps for thermal comfort”. If that’s right, then around 23 million of Britain’s 28 million homes are heat pump ready. 

It may still be worth improving your insulation, however, because of the trade-off between up-front costs and annual bills. Before I got the heat pump, I had already insulated the roof and two walls at a total cost of around £7,000. 

When I later had a firm in to measure the rate at which the house loses heat, it found that I could have skipped the final bit of insulation work (saving £2,000), and the heat pump would still have coped – but annual bills would have been higher. If you are unsure, it might pay to measure your thermal efficiency earlier than I did, through companies like Veritherm or Build Test Solutions. 

It’s easy to check if your home is heat-pump ready 

The reason heat pumps need more insulation than boilers is that they don’t get the radiator fluid as hot. Whereas Vaillant UK, which manufactures boilers, heat pumps and heating systems, says your combi should be set to 60-70 Celsius, while a heat pump generally operates at 45C or 50C. 

The quick way to check if your home is ready is simply to turn the boiler’s flow temperature down to 50C and run it 24/7 (leave the room thermostats as before). 

If this keeps you warm enough during a cold snap then you are heat pump ready. You will probably also reduce your heating bill and emissions right away. 

It’s true, installation can be a bit of a faff

There’s quite a lot of plumbing and wiring to do with a heat pump installation, which all takes time, and you may also need – as I did – some bigger radiators and a bigger hot water tank. 

My installers, Elite Renewables, took a fortnight, but organised work so that the switchover from the boiler to the heat pump happened in a single day, so I was never without heat. 

You do need to change the way you think about heating 

The misery of gas boilers in a cost of living crisis is that the way to economise is to be cold most of the time. 

Heat pumps are just the opposite: because the flow temperatures are lower, you need to run them for longer and they work more efficiently that way. It may be counterintuitive, but you stay at a comfy temperature and save money by leaving them on.

I heat the kitchen, living room and bathroom for 18 or 19 hours per day. 

Smart thermostats are worth installing

If you have any rooms that don’t need heating full-time – like bedrooms during the day – it’s a good idea to install smart thermostats and radiator valves (TRVs) to control them separately. 

Having a mobile app to sync with them also lets you turn the heating on a day before you return from that winter holiday so the place is cosy when you get back. 

There are many brands to choose from, but I find Drayton Wiser devices work well and the app is easy to use. 

Use cheap overnight electricity

Since you need to run the heat pump more or less full time, it can also make sense to switch to a time-of-use tariff, like Economy 7. 

I use cheaper overnight electricity to heat the hot water tank between midnight and 2am and then preheat the house until 7am, which means less energy is needed during the day when it’s dearer. 

I calculate that this saved me roughly £40 a month during the first winter (but it probably wouldn’t save money in a poorly insulated home and might even cost you more). 

Overnight electricity also typically emits less carbon because demand is low, meaning fewer fossil power stations burn during those hours.

Invest in heat pump monitoring 

The wall box controls for my Mitsubishi heat pump are not especially user-friendly, and I hear the same of other brands. 

The functionality of the internet adaptor (which cost £120) and mobile app is limited, but having it meant I received an email alert when a problem in the plumbing hobbled the heat pump’s efficiency and would have meant a nasty surprise when the next bill arrived. 

The alert meant I could call in the installers to fix the problem right away, so the adaptor has probably paid for itself already. 

Get rid of any remaining gas appliances

Once you have a heat pump you may as well go all-in for electricity. 

If you replace the gas cooker with an induction hob, for example, you can then tell your energy supplier to disconnect the gas supply and remove the meter; that way you’ll save another £100-odd per year. 

Remember, as more and more households abandon gas, gas network charges are likely to rise sharply. 

Save more energy with the ‘weather compensation curve’

Most heat pumps need a flow temperature of 50C to keep a home warm when the temperature outdoors is -2C. But when the weather is milder, they can provide enough heat at lower flow temperatures – I’ve had mine down to 30C recently – which means they save even more energy. 

You can adjust this manually easily enough, using the wall box controls. Once you have an idea of the flow temperatures you’ll need for the normal range of outdoor temperatures, you can set the “weather compensation curve” to make these changes automatically. 

Switch energy tariff

With a heat pump, your emissions will fall whatever your tariff, but will only get to zero with a wholly renewable supply (I like 100Green). 

With a heat pump running on carbon-free electricity you may get another kind of warm feeling: the knowledge that you are raising the chances of leaving a survivable planet to your children.