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Heat pump or gas boiler? Which way should I go?

My gas boiler is on its last legs. More running problems every year. It’s cranky, and spluttery, and doesn’t seem to want to get started on cold mornings. I know how it feels.

So, I need a replacement. But do I get a new gas boiler, or a heat pump? It’s a complicated business. Whatever decision I take will cost thousands. And it’s not helped by there being a concerted media campaign to spread negative misinformation about heat pumps.

This blog is my pros and cons so far, and then the decision at the end. First disclaimer: I work on climate change, so my inclination is against using gas. But second disclaimer – I’m from Yorkshire, so I won’t be spending anything I don’t have to.

First, my house is pretty typical – it’s a mid-terrace in Bradford, built around 1910. Solid wall. Double glazing. Some insulation, overall EPC C. Small garden, so ground-source heat pumps are out – I’d be after an air-source heat pump. My energy supplier (Octopus) are pretty big on rolling out heat pumps, but my type of house is not one they’re doing at the moment. I guess they prioritise bigger houses with better insulation – the costs probably work out better for those types of home.

I’ve got five main factors: i) upfront cost, ii) running cost, iii) environment, iv) comfort and convenience v) future-proofing. Here’s how the heat pumps and gas boilers match up for me on those five things:

1) Upfront cost. Right now, the Government has a grant of £7,500 for domestic heat pumps. I’ve been quoted £13,500 for a system including all installation, some new radiators, parts, a new hot water tank, etc. So the cost to me is £6,000. The cost of a new gas boiler is going to be £2,000-£2,500. But, a heat pump is going to last 30 years, and a gas boiler half that long. So I should be comparing 1 heat pump with the cost of 2 gas boilers. Overall: not a lot in it.

2) Running cost. 1 kWh of gas into a boiler gives me roughly 0.8kWh of heat. 1kWh of electricity into a heat pump will give me 3-4kWh of heat – how much depends on many factors, such as my home’s energy efficiency. Overall, heat pumps are way more efficient. But, electricity is more expensive than gas – around 27p/kWh versus 7 p/kWh for me at the moment. Overall, I think I can expect my energy bills to be slightly lower, but there won’t be a lot in it. As time goes by, my heat pump is likely to get more efficient – the more used to it I am. And as I’ve got an induction hob, I won’t be using gas at all, so I can get it disconnected – no daily standing charge for gas anymore.

3) Environment. Overall, gas is currently the biggest part of my carbon footprint. It will be a major part for most people. Switching to a heat pump will save around 1.5 tonnes of carbon dioxide every year – it’s the single biggest thing I can do to cut my individual impact on climate change.

4) Comfort and convenience. Heating your home with a heat pump is different. Gas boilers have a pretty immediate effect. If it’s cold, ramp up the boiler. Peaks and troughs of energy use. With heat pumps it’s all about maintaining a level temperature – so a more constant drip-feed of energy. So, two things. First, it helps if your house is well-insulated. But that’s also true for a gas boiler: the less energy you waste, the less you need to put in. Second, I will need a hot-water cylinder, rather than just being able to fire up my boiler whenever I want a blast of hot water. So that’s space I’ll need to find. And I will need some bigger radiators in some rooms too. Friends who have heat pumps say the installation was fine, and their house is toasty.

5) Future proofing. Two things. First, the writing is on the wall for gas. Climate change impacts are already a problem. They’re only going to get worse. So the pressure on Governments to do more will only increase. If I buy a new gas boiler now, it will last 15 years. It is likely that in those years, Governments will increasingly try and push people to not use gas, as they are already doing. And in 15 years, no-one will be buying new gas boilers, so I’ll need a heat pump then anyway. May as well do it now. Second, electricity is likely to get cheaper, as more cheap renewables get built. Electricity is also mainly pricey now because its price is tied to the price of the most flexible unit of production – which is expensive gas power stations. It seems inevitable that Government will fix this anomaly at some point – it's crazy that most electricity is cheap, but its wholesale price is determined by the price of the most expensive element of it.

Overall, I think the cost and comfort issues are neutral, the environmental benefits and future proofing are strong positives in favour of heat pumps. That’s also the experience of the people I know who’ve already got heat pumps, and the advice from the independent surveyor who came round the other month. I think I will go for it. I’ve chosen to go with Marvel in Doncaster, who specialise in heat-pump installations. So far they’ve been excellent – upfront about the cons as well as the pros, patient under a barrage of simple questions, and clear on costs and technicalities.

Part two in a month’s time will be on how the installation went, then part three will be on how the costs have worked out....