‘My heat pump works so badly in winter I have to use my wood stove’
Homeowners resort to pollution-heavy alternatives to pick up the slack from net zero devices
“I’m seriously considering replacing my heat pump with a modern modulating condensing low-temperature oil boiler that would have a likely payback period of five years. A replacement heat pump would never pay for itself.”
They are supposedly the greenest form of home heating. But even in the most well-insulated properties, homeowners are turning to
polluting wood-burning stoves to pick up the slack from inefficient
heat pumps.
Among them is Stephen Coombs, whose home is the model of energy efficiency.
“I’m not a net zero nut,” he says, “but I have to say my house is normally a consistent temperature and I like it very much.”
To heat the property, Coombs was presented with two choices: oil or electricity. He ultimately opted for the latter, conscious that an increasingly green-minded government was trying to push off-grid homes away from oil-fired boilers and
towards electricity-powered heat pumps.
For the most part, he says the heat pump performed as expected. The machine’s coefficient of performance (COP, the measure of a heat pump’s efficiency) averaged at 2.2. A typical gas boiler, by contrast, has a much lower average COP of between 0.7 and 0.8.
“If you want to be comfortable with underfloor heating and heat a room to 21C, you want the surface temperature to be around 27C,” Coombs explains.
Radiators, by contrast, must reach higher temperatures of around 35C to heat a room to the same temperature. But there’s a big snag.
“During the last couple of weeks with freezing temperatures, the COP fell to 1.7,” Coombs says. “With electricity at four to five times the cost of gas, it is easy to calculate that my heat pump costs around twice that of a 90pc efficient condensing gas boiler.”
To supplement his heat pump, Coombs has begun using a wood stove. Though still popular for those looking for an extra boost to their heating on cold winter nights, there are concerns about the health and potential environmental impacts of burning wood in your home.
A number of home owners have told The Telegraph that they have had to resort to burning additional fuel because their heat pump cannot make their home warm enough in sub-zero temperatures.
One reader said that she had “burnt half a rainforest” heating her home, on top of using a gas heater.
Heat pumps lose efficiency in cold weather because the machines must expend more energy to extract the same amount of heat from the air outdoors.
Analysis by the Energy Utilities Alliance (EUA) found that
heat pumps cost around £4 more per day to run in sub-zero temperatures than gas boilers. Notwithstanding its effect on the environment, logs are expensive.
“Legislation requires that the wood has a moisture content of less than 20pc,” explains Coombs. Logs must be either kiln-dried or stored for several years before they can be used, driving up the price of wood.
“I feel this cost should be factored into the heat pump vs gas comparison,” Coombs says.
“With the current drive for increased wind and solar generation, electricity can only become more expensive.
“I’m seriously considering replacing my heat pump with a modern modulating condensing low-temperature oil boiler that would have a likely payback period of five years. A replacement heat pump would never pay for itself.”
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