Heat pumps will not work for older UK homes which lack the necessary space and insulation, the UK boss of one of the largest makers of the devices has warned. 

Heat pumps are a great solution for heating new homes with plenty of lagging and room to accommodate the larger system, said Vonjy Rajakoba, managing director of Bosch UK.

But much of the UK's Victorian housing stock is unsuitable for installing them and hydrogen-burning boilers are the future for those homes as the gas becomes cheaper to produce.

“At low temperature 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,” Mr Rajakoba said in an interview.

“It's important really to emphasise that it's not hydrogen against heat pumps, there's a space for both technologies,” he added. “There is space for heat pumps for new construction. At low temperatures you need well-insulated homes, you also need space for heat pumps.”

The UK gas network is being upgraded with plastic pipes to accept the gas and the Government wants new boilers to be capable of burning hydrogen from 2026.

Supplying hydrogen-ready boilers which can burn today’s methane, hydrogen gas or a mix means that the switchover to the new gas can be done simply when the greener fuel is available in sufficient quantity, he said.

“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,” said Mr Rajakoba.

Hydrogen is a controversial gas for home heating because of how much cheaper heat pumps can be to run. Using heat from the environment either in the air or the ground, and pumping it inside, they use existing energy, vastly improving their efficiency. The principle is similar to that of a refrigerator. 

For hydrogen to be carbon-free, it must be made using green electricity from solar, wind or nuclear power plants. Water molecules are split using that electricity into hydrogen and oxygen. But this conversion means less efficiency and the same electricity could simply power a pump.

Hydrogen can be made from methane, with the carbon dioxide byproduct buried under the sea in so-called carbon capture, but this exposes hydrogen to volatile natural gas prices and adds the expense of storing the CO2 forever.

Complicating matters further, a full heat pump setup is more expensive to buy and fit, while hydrogen-fired boilers are similar in price to today’s methane-burning models. Much depends on the price of hydrogen.

“Like any new industry we do not have the economy of scale. The hydrogen of today is expensive,” he said. “But that gap is reducing.”

Bosch makes both heat pumps and gas boilers for the UK market under its Worcester brand.

The company has been in the UK for 125 years and Britain was the first foreign market it entered after being founded in Germany.

It is largely owned by a charitable foundation set up following the death of founder Robert Bosch.

Known in the UK for its power tools, the firm is one of the largest makers of car parts in the world and most of its sales come from sales to companies including Volkswagen and Vauxhall owner Stellantis.

While the US and EU are ramping up subsidies for green technology, Mr Rajakoba said the UK could kick-start industry by cutting electricity prices, which for heavy users are among the most expensive in Europe.

He also implored the Government to focus on growth in the Budget rather than other distractions.

“Growth was not at the forefront,” he said. “But now, growth, growth, growth, growth, that's the most important thing to drive the country forward.”