Key takeaways
- A heat pump’s running cost is set by its efficiency and the price you pay per unit of electricity, not by the technology alone.
- A good system delivers roughly three to four units of heat per unit of electricity, which is how it competes with gas.
- Insulation, a low flow temperature and the right tariff make the difference between cheap and expensive running.
- A heat pump on a special heat pump electricity tariff can cut running costs noticeably.
Heat pumps are often described as cheap or expensive to run, and both can be true. What decides it is how efficiently the system works and what you pay for electricity. Here is what actually drives the cost.
Efficiency is everything
A heat pump’s efficiency is measured by how many units of heat it produces per unit of electricity it uses. A well-designed system runs at roughly three to four to one, which is what lets it compete with a gas boiler even though electricity costs more per unit than gas. The higher that figure, the lower your bills.
What pushes the cost up or down
Three things move the needle. First, insulation: a leaky home loses the heat as fast as the pump makes it. Second, flow temperature: a heat pump set to run at a lower water temperature across bigger radiators or underfloor heating is far more efficient than one forced to run hot. Third, your tariff: several suppliers offer heat pump tariffs with cheaper electricity, which can change the numbers significantly.
The catch: a heat pump dropped into a poorly insulated house and set to run hot can cost more than the gas boiler it replaced. The technology is only as cheap as the setup around it, so the install and the home matter as much as the unit.
How to keep running costs low
Insulate and draught-proof first, size the radiators or fit underfloor heating so the system can run at a low flow temperature, and shop around for a heat pump electricity tariff. Run it steadily rather than blasting it on and off, which suits how a heat pump works. For the wider comparison, see heat pump vs gas boiler costs and our UK heating cost index.
FAQ
Are heat pumps cheap to run?
They can be, when the home is insulated, the system runs at a low flow temperature and you are on a suitable tariff. In those conditions a heat pump competes with or beats gas; in a leaky home set to run hot, it can cost more.
Does a special tariff help?
Yes. Several suppliers offer heat pump electricity tariffs with cheaper rates, which can cut running costs noticeably compared with a standard tariff.
Why is flow temperature important?
A lower flow temperature lets the heat pump run more efficiently, producing more heat per unit of electricity. Bigger radiators or underfloor heating make a low flow temperature comfortable.