Benefits of air source heat pumps

Unlike resistive electric heating, a heat pump moves heat rather than creating all of it directly from electricity. That means one unit of electricity can deliver multiple units of useful heat under the right conditions.

This is what makes heat pumps so important in long-term decarbonisation plans, but it also means they need to be assessed differently from a boiler replacement.

That efficiency advantage is especially important when the alternative is direct electric heating such as panel heaters, electric boilers, or storage heaters. Compared with those systems, an air source heat pump can often be a much more efficient way to provide the same useful heat.

Heat pumps tend to work best in homes with decent insulation, sensible heat distribution, and realistic expectations around flow temperatures. Homes that are very drafty or poorly insulated can still use them, but the economics and comfort outcomes are usually less straightforward.

Government grants can also materially reduce the upfront cost and change the comparison versus a like-for-like boiler replacement.

A heat pump may use much less input energy than a boiler, but electricity is usually more expensive per kWh than gas. That means the running-cost picture depends on both heat pump performance and the relative price of gas and electricity.

This is exactly why scenario modelling is useful: the right answer is not the same for every home or tariff.

Compared with direct electric heating, however, the case is often much stronger because a heat pump can deliver more heat from each unit of electricity bought. The economics can become stronger again if the home also has a battery and access to cheap night-time electricity. In that setup, some of the electricity used to support heating can effectively be bought overnight at a much lower rate and shifted into daytime use.

For some homes, the real decision is not simply boiler versus heat pump. It may involve radiator upgrades, hot water storage, future solar, or the wider direction of the home over the next 10 years.

A good comparison should account for both upfront system cost and longer-term running costs, not just the sticker price of the heat pump unit itself.