Is my heat pump using too much energy?

Heat pumps usually work best when they run steadily at a low flow temperature instead of blasting heat in short bursts.

Flow temperature is the temperature of the water leaving the heat pump for the radiators or underfloor heating. Lower flow temperatures usually improve heat-pump efficiency, provided the radiators can still release enough heat to keep the rooms comfortable. Weather compensation can automatically vary flow temperature according to outdoor conditions.

Large temperature swings are not ideal. If the home is allowed to cool substantially overnight, the system may need a higher flow temperature or a long recovery period in the morning. A common starting point is around 21°C during occupied daytime periods with only a small overnight setback, such as 19°C to 20°C.

An immersion heater is effectively direct electric resistance heating. Leaving it running unnecessarily can increase electricity use: if your bills seem unexpectedly high, check whether the immersion heater is operating more than intended.

Oversizing is not a harmless safety margin. A unit that is too large can cycle on and off more often, which can reduce efficiency. Flexible or heat-pump tariffs can improve the economics, especially if you can shift some electricity use into cheaper periods.

If your heat pump is comfortable but expensive to run, ask the installer to review flow temperature, the weather-compensation curve, thermostat schedules, zoning, immersion-heater operation and cycling frequency. Change one setting at a time and give the system time to settle before judging the result.