Your First Year With a Heat Pump: Month by Month

What is the first year with a heat pump actually like? This guide walks through a typical year, starting with an autumn installation, covering what you will notice, what to check and where the costs fall. It is a general guide based on how heat pumps operate, not one household's diary, so your own year will vary with your home, your installer and the weather.

The Example Home

To put figures on the year, we use the site's standard example: a home needing 11,500 kWh of heat a year for heating and hot water, roughly a typical semi-detached house, with a heat pump running at a seasonal COP of 3.2. It uses about 3,594 kWh of electricity a year, which costs about £946 at the October 2026 price cap (26.32p/kWh, Ofgem, 1 October 2026 to 31 December 2026). The same heat from a 90% efficient gas boiler would cost about £1,018 on unit rates (7.97p/kWh). Standing charges are extra in both cases.

Month 1: Installation and Commissioning

Installation usually takes two to four days: the old boiler comes out, a hot water cylinder goes in, pipework is adapted, the outdoor unit is fitted, and any undersized radiators are replaced. Commissioning is the most important hour of the job. The installer should set the weather compensation curve, flow temperature and hot water schedule for your home, show you the controls and app, and give you the MCS certificate and commissioning paperwork.

The first surprise for most people is that radiators feel warm rather than hot. That is expected: heat pumps run at lower flow temperatures and heat the house steadily rather than in bursts.

Month 2: The Learning Curve

The main adjustment is to stop treating the system like a boiler. Turning the heating off and on, or turning the thermostat up to "boost", usually makes a heat pump less efficient. Leaving it to run steadily under weather compensation, with at most a modest night setback, generally works best. If rooms are too cool or too warm, ask the installer to adjust the curve rather than overriding it.

Months 3-5: Winter and Cold Snaps

Midwinter is when the heat pump works hardest and uses the most electricity. Efficiency falls as the outdoor temperature drops, and on cold, damp days the outdoor unit runs short defrost cycles, sometimes with visible steam. A correctly sized system keeps the house at its set temperature through a cold snap; if it cannot, the heat loss calculation or settings should be checked. This is also a good time to look at a heat pump or time-of-use tariff, comparing the supplier's current rates with your actual usage.

Month 6: Spring

As the weather warms, the heat pump runs more efficiently and uses much less electricity. By now you can compare a full winter's electricity use with your previous fuel bills, adjusting for any difference in prices, to see how the system is performing.

Months 7-9: Late Spring to Summer

Space heating switches off for most of the summer. The heat pump typically runs only to heat the hot water cylinder, often for a short period each day, so electricity use drops to a small fraction of the winter level. If you have solar panels, scheduling hot water for the middle of the day can use more of your own generation.

Months 10-12: Late Summer to Autumn

Heating returns gradually as evenings cool. Book the first annual service, which most manufacturers require to keep the warranty valid, and check that the weather compensation settings still suit the house going into the second winter.

The Annual Picture

Most of the year's electricity use falls between November and March. Against mains gas, the running-cost difference on this example is small (about £72 a year on unit rates, or about £180 if you also drop the gas standing charge); against oil, LPG or electric heating it is much larger. See our worked savings examples by previous fuel. Upfront, the median installed air source heat pump cost £12,908 before the £7,500 Boiler Upgrade Scheme grant in 2026 Q2 (DESNZ), about £5,400 after it.

Frequently Asked Questions

What happens in the first month with a heat pump?

Installation usually takes two to four days, followed by commissioning, when the installer sets the weather compensation curve, flow temperature and hot water schedule and shows you the controls. Radiators feel warm rather than hot; that is normal at the lower flow temperatures heat pumps use.

When does a heat pump use the most electricity?

In the coldest months, roughly November to March, when heating demand is highest and efficiency is lowest. In summer it typically heats only the hot water cylinder, so electricity use falls sharply.

How much does a heat pump cost to run over a year?

On our standard example (11,500 kWh of heat a year, seasonal COP 3.2) a heat pump uses about 3,594 kWh of electricity, about £946 a year at the October 2026 price cap (26.32p/kWh). A 90% efficient gas boiler would cost about £1,018 on unit rates for the same heat. Your figure depends on your home's heat demand and how well the system is set up.

Should I change tariff after installing a heat pump?

It is worth checking. Some suppliers offer heat pump or time-of-use tariffs with cheaper periods, but rates are regional and change often, so compare the supplier's current rates with your usage before switching.

Does a heat pump need servicing?

Yes. Most manufacturers require an annual service to keep the warranty valid; check your warranty terms.

Is this one family's real diary?

No. Earlier versions of this page presented a family diary; we could not evidence it, so we replaced it with this month-by-month guide based on how heat pumps operate and on the published price cap.