Ground and air source heat pumps are being promoted as an alternative to traditional central heating — but a top heat pump manufacturer is now advising those with older homes not to install them.
Heat pumps move heat from one place to another using a compressor and a circulating structure of liquid or gas refrigerant to extract heat from outside sources and pump it indoors. They are considered energy efficient and therefore environmentally friendly due to being able to recycle heat as well as generate it. Heat pumps can also lower fuel bills and reduce home carbon emissions if installed well.
However, Bosch, which manufacturers heat pumps, warns the technology may not work in some older homes in the UK.
Why don't heat pumps work in older homes?
Bosch UK managing director Vonjy Rajakoba told the Daily Telegraph heat pumps are excellent for new homes, but much of the UK’s housing stock lacks the required room.
He said: “At low temperatures, you need well-insulated homes, you also need space for heat pumps for the external unit and also the tank, so you need to have the sort of home which is adequate around the heat pumps.”
Experts advise that installing an air source heat pump should only be in insulated buildings as this helps when recycling heat as well as efficiency being higher when the flow temperature from the heat pump is lower. Meanwhile, in a poorly insulated building, a higher flow temperature is required meaning the heat pump will cost more to run and have higher carbon emissions.
What type of boiler does Bosch recommend for older homes instead?
Rajakoba said that hydrogen-burning boilers were the more suitable option for older homes. Hydrogen boilers are a new technology which could help to lower energy costs and decrease carbon emissions.
A hydrogen boiler works in a very similar way to natural gas boilers. Whereas natural gas boilers burn gas (or methane), hydrogen boilers burn hydrogen. This creates hot flue gases that can be used to heat water. The main by-product of burning hydrogen gas is water, instead of carbon dioxide like natural gas.
“We think in the UK with the fleet of Victorian houses or period houses and so on, hydrogen, or in the interim, hydrogen-ready boilers are the solution,” he said.
“It's important really to emphasise that it's not hydrogen against heat pumps, there's a space for both technologies.”
