Setting Heating Controls for a Heat Pump System

Why Heat Pumps Want a Different Approach to Heating Controls

If you have just had a heat pump installed, or you are planning one, the single biggest change you can make is to stop thinking in terms of quick bursts of heat. A gas boiler is often sized generously and can blast a room up to temperature in twenty minutes. A heat pump works best at lower flow temperatures, often between 35°C and 45°C rather than the 65°C to 75°C a boiler might run at, and it delivers that gentler heat steadily over a long period. Set your controls as though you were driving on a motorway rather than sprinting between traffic lights: smooth, consistent and planned well ahead.

The good news is that this usually costs you nothing but a change of habit. In many homes it also cuts running costs, because a heat pump running at a low flow temperature is far more efficient than one being pushed hard to reach a high one.

Set the Schedule Around Your Daily Routine, Not Around Panic

Start by mapping out when your home actually needs to be warm. Most households want comfort from around 6.30am to 9am, then again from roughly 4pm until bedtime. Everything in between can usually drop back, and overnight can drop further still.

Because a heat pump heats slowly, you need to start earlier than you would with a boiler. If you want the living room warm by 7am, set the heating to come on at 5am or even 4.30am in cold weather. A 16°C overnight setback is a sensible starting point for most well-insulated UK homes, and 15°C to 17°C is a reasonable bath for the daytime if nobody is in.

• Morning: start two to three hours before you get up.
• Daytime: drop to 16°C to 17°C if the house is empty.
• Evening: begin warming again by 2.30pm to 3pm for a 5pm comfort level.
• Overnight: 15°C to 16°C is usually enough, and lower if your insulation is good.

Use Weather Compensation and Leave the Flow Temperature Alone

Most modern heat pumps can adjust their flow temperature automatically based on the outdoor temperature. This is called weather compensation, and it is the closest thing the industry has to a magic setting. On a mild 10°C day, the heat pump might run at 35°C. On a frosty morning it may lift to 45°C or slightly more. The system does the thinking so you do not have to.

Once weather compensation is set up, resist the temptation to nudge the flow temperature up when you feel chilly. That is the boiler habit creeping back in. Instead, raise the room thermostat target by half a degree and give it a few hours. The heat pump will respond, but gently.

If your installer has left you with a fixed flow temperature, ask them to enable weather compensation or at least set a sensible curve. It is often the difference between a system that ticks over cheaply and one that works hard for little reward.

Trust the Thermostat, Not the Radiator Valves

Room thermostats and radiator valves do different jobs, and confusing them causes no end of frustration. The room thermostat sets the target temperature for the whole zone. The thermostatic radiator valves balance individual rooms so that, for example, a sunny south-facing bedroom does not overheat while a north-facing study stays cold.

Set your thermostatic valves once, room by room, and then leave them. Turning a valve down to save money when the room is already cool just starves the heat pump of the water it needs to circulate, which can actually reduce efficiency. A better approach is to balance the system properly in the first place, then step back.

• Living areas: valves open fully or set high, typically 4 or 5.
• Bedrooms: slightly lower, around 3, unless you like a warm room.
• Spare rooms: turn the valve down but never fully off, to avoid trapping cold spots.

Get the Hot Water Schedule Right Too

Domestic hot water is often the part of the system people overlook, and it can account for a meaningful slice of your annual running costs. Because a heat pump heats the cylinder more slowly than a boiler, you need to give it a decent window. One long, well-timed reheat is nearly always better than several short top-ups.

A common and effective setup is a single early-afternoon or early-evening cylinder cycle, timed so the water is ready for baths and showers. Set the cylinder to around 48°C, with a legionella cycle to 60°C once a week if your installer recommends it. If you have a solar photovoltaic array, shifting the hot water cycle to the sunniest part of the day is a smart, low-effort saving.

Small Habits That Make a Big Difference

Once the schedule is set, a few daily habits will help everything run smoothly. Keep internal doors open where you can, so heat circulates rather than pooling in one room. Avoid drying washing directly on radiators, which blocks the heat you have paid for. And try not to override the schedule for a single cold hour; a brief boost at low flow temperature does very little, whereas leaving the system to run its course gives you a steadily warmer home.

Finally, give any change at least a week before judging it. Heat pumps reward patience. Tweak the timings, watch how the house feels, and adjust in small steps. Done well, your heating controls will fade into the background, quietly keeping the house comfortable while using as little energy as possible.