In our journey to decarbonising our lifestyle the switch from a gas boiler to an electrically-driven heat pump was the single biggest carbon dioxide reduction we did.

The reliability over 8 years has also been excellent. Our old gas boiler used to have about one issue each year requiring a call out and repair in addition to the annual service. Scarcely a year went by without a breakdown and the wait for a plumber to help get the boiler going again. Each year we were told “the spare parts for your boiler may not be available in the future because it is an old model” (it wasn’t that old) and “have you considered one of our new high efficiency boilers as it will save you lots of money on your bills” (it wouldn’t have saved that much – 95% efficient compared to 78%). Finally around 9 years ago I made the decision to go to an air source heat pump instead. Most of the plumbers back then didn’t even know what one was. Instead of a domestic heating and plumbing company we needed to go to a heating, ventilation and air conditioning (HVAC) supplier who was more used to offices, shops and hotels than domestic installations (we were in fact only their second domestic installation).

A heat pump uses much less purchased energy to heat the house because heat pumps work to move heat from outside air. Yes, cold air outside still contains a lot of heat: air leaving the outside unit is much colder than the air going into the outside unit and it is that heat difference which is the heat which is transferred indoors. So what you pay for is the electrical power needed to drive the compressor to move the fluid round the heat pump circuit and the small amount of electrical power needed to turn the fans that move the outside air through the outside unit (and the indoor air through the indoor units in the case of an air-to-air setup or the pump to move the warm water round the radiators in the case of an air-to-water setup). This means that there is much more heat delivered than energy used to pump it and “efficiency” (what you get compared to what you pay for) is ludicrously large – so much so that in the world of heat pumps it is called Coefficient of Performance (or CoP). Values can easily be in the range 3 to 4 and even higher (ours averages out as 4.2 over the year – 420% if comparing to a gas boiler efficiency). Even with gas costing less per kWh than electricity, the very high CoP means it is easy to pay less with a heat pump to deliver the same heat into the dwelling. Perhaps the best thing is that because we’ve stopped burning gas, our carbon dioxide emissions are really low now. Over the last 8 years we’ve consistently paid less even when the gas prices were low compared to today. Our heat pump has been a real win-win-win-win when delivering similar levels of thermal comfort as before.

• win – reduced use of energy
• win – reduced running costs
• win – reduced carbon dioxide emissions
• win – improved reliability

One last thing. Stories of low levels of heat output or needing to massively increase your radiator sizes or needing underfloor heating and needing upgraded insulation have often been repeated. This is because most early heat pumps had lower radiator temperatures than gas boiler systems (the same amount of heat, but just delivered as a warm rather than a too-hot-to-touch radiator – think 3 cups of warm tea compared to 1 cup of near boiling water – same heat but at a lower temperature). However now we’re seeing the first drop-in replacement models delivering heat at exactly the same temperature as your old gas boiler. What does this mean? It means these hotter heat pumps can feel just the same as a gas boiler but just with much lower energy use, lower running costs, lower carbon dioxide emissions, and with expected higher reliability too. “Your house is not suitable” is becoming a phrase of of the past…

If you are considering changing your boiler then consider instead a heat pump.

Read our old (2021) article on installing a heat pump here

Note that since 2022, the UK grant scheme is the Boiler Upgrade Scheme with upfront grants of up to £7500 towards the installation of an approved heat pump.

Read our reference articles on heat pumps:

How do costs compare? Read more here

Are carbon dioxide emissions really lower? Read more here

Learn more about heat pumps here