Heat Pump Controls

Heat pump controls work differently from the simple on-off thermostat many people know from a boiler. Instead of heating water to a fixed high temperature and switching off when a room reaches its target, a heat pump often runs for longer at a lower temperature, with weather compensation adjusting the flow temperature as outdoor temperature changes. On a mild day the water runs cooler, and on a cold day it runs warmer, which keeps rooms steady rather than swinging between hot and cold.

That steady approach feels unfamiliar at first. Radiators may feel only warm to the touch, and the system may run when the house already seems comfortable, because it is maintaining temperature rather than chasing it in bursts.

The main control elements are the weather compensation curve, the room thermostat or room influence setting, timers or schedules, and separate hot water control. The curve sets how flow temperature responds to outdoor temperature, and a curve set too steep wastes energy while one set too shallow leaves rooms cold on frosty days. Room influence lets a living room sensor nudge the curve, which helps when internal gains from cooking or sunshine change the picture.

Hot water control is separate because a cylinder needs periodic hotter water, and some systems schedule a weekly hotter cycle. Understanding which setting does what prevents the common confusion of turning one dial and accidentally changing both heating and hot water behaviour.

Before changing anything, photograph the existing settings and read the controller manual for this exact model, since menus and terms vary between makers. Note the current curve, any setback temperatures for night or away periods, and the hot water schedule, then change one thing at a time and observe for several days before judging the result.

Check whether the controller offers remote access, what happens after a power cut, and whether settings are locked behind an installer menu. A household that cannot adjust a basic schedule without calling an installer will struggle to live comfortably with the system.

In the EU, control requirements for heating systems appear in national building regulations and product rules under the EPBD framework, and some member states require specific control functions, such as room-by-room control, in new or renovated systems. The exact duties therefore depend on the country and on whether the work is new build or renovation.

In the UK, building regulations set expectations for heating controls, and MCS standards cover heat pump control design and handover. Scotland, Wales and Northern Ireland have their own building standards, so the applicable control requirements should be checked for the property location.

A frequent mistake is running a heat pump like an old boiler, with short high-temperature bursts and deep night setbacks that force a long, hard recovery in the morning. Another is letting two controls fight: a room thermostat calling for heat while a timer says off, or a smart thermostat overriding a weather curve in ways nobody documented.

A third mistake is never revisiting the curve after insulation or radiator changes, so a system tuned for a draughty home keeps overheating an improved one. After any fabric or emitter change, the curve deserves a fresh look. It also helps to keep a seasonal diary for the first year, noting the curve setting, outdoor temperature and room comfort each month, because a curve that felt right in October may prove too steep in February or too shallow in March, and a written record turns vague impressions into a setting change that can be explained and, if needed, reversed.

Keep the controller manual, a written note of the commissioned settings, the weather curve values, the hot water schedule and any handover notes. If settings are changed later, add a dated note so the next person can see what was tried and why.

Ask a qualified installer: what curve have you set and why, how should we adjust it seasonally, how does room influence work on this model, and what hot water cycle is scheduled. A clear handover on those points is part of a good installation, not an extra.