Three controls, one job
Heating controls answer three separate questions.
- Where does the heat go? That is the job of zones.
- When is heat provided? That is the job of timers or schedules.
- How warm should it get? That is the job of the setpoint, the target temperature a thermostat tries to hold.
Used together, they let a home deliver comfort in the rooms and at the times people need it, rather than heating the whole building to the same temperature all day. Used badly, they can add complexity without any benefit, or even make people uncomfortable enough to override them constantly.
Zones: heating the parts you use
A heating zone is a part of the home with its own temperature control. In a simple house the whole building may be a single zone, with one thermostat and one timer. In others, upstairs and downstairs are separate, or individual rooms have their own radiator valves or electric heater controls.
Common ways to create zones include:
- Thermostatic radiator valves (TRVs). These sit on a radiator and open or close depending on room temperature. They let you keep a seldom-used room cooler.
- Zone valves and separate thermostats, which divide a wet central heating system into areas, such as day and night zones.
- Smart radiator valves or room sensors that allow schedules per room.
- Separate controls on underfloor heating loops or electric heaters.
Zoning makes the most sense where parts of the house are used very differently, for example a spare room, a large hallway or a home office. In a small, open-plan flat it may add little.
There are trade-offs. Closing off a room does not mean its heat demand disappears, because heat will still flow from warm rooms through walls and doorways into cooler ones. Keep internal doors closed where you can, so the unheated room does not simply draw heat from the heated one. A room that gets very cold is also more prone to condensation, so check the guidance on condensation control, and keep at least a minimum level of background warmth in rooms where damp has been a problem.
Timers: heat when it is needed
A timer or programmer switches heating on and off at set times. A typical pattern is heat before waking, a gap while people are out, and heat for the evening. The aim is to avoid heating an empty house while keeping it comfortable when someone is in.
A programmable thermostat combines a timer with temperature control, allowing different setpoints at different times. Some learn patterns or respond to whether people are home, which smart home devices sometimes offer. The benefit depends on whether the schedule matches how the household really lives. A schedule that nobody can be bothered to adjust when plans change can waste as much as no schedule at all.
Things to consider when setting a timer:
- Warm-up time. A heavy, poorly insulated house takes longer to warm up than a well-insulated one. Start early enough to reach the desired temperature when you need it. Some controls calculate this automatically, often called optimum start.
- Cool-down time. A well-insulated home loses heat slowly, so heating can switch off before you leave or go to bed without much noticeable change.
- Heating system type. Boilers generally respond quickly. Underfloor systems and heat pumps often respond more slowly and may work better on steady or gently varying schedules, so follow the installer’s guidance. This is discussed in the article on how heat pumps work.
Setpoints: choosing the temperature
The setpoint is the temperature you ask the system to maintain. Lowering it generally reduces the heat the home loses, because heat flows faster when the difference between inside and outside is bigger. So a lower setpoint tends to use less energy, other things being equal.
There is no single right number. Comfort varies with age, clothing, activity and health. Some people, such as older adults, babies or people with certain health conditions, may need warmer rooms, and living in a home that is too cold can be harmful. Public health bodies in different countries publish recommended minimum indoor temperatures, and it is sensible to check those instead of aiming for the lowest possible setting for its own sake.
Small changes in setpoint can matter, but the amount saved depends on the building and on the outdoor temperature, so be careful with confident figures you may see quoted elsewhere.
Myths about leaving it on or turning it off
A common question is whether it is better to leave the heating on low all day or to switch it on and off. The answer depends on the building. In general, a house loses heat at a rate that depends on the temperature difference. Keeping it warm all day means a higher average temperature and so more heat loss than letting it cool when empty. But for some systems, particularly heat pumps and in very well-insulated homes, steady running can be more practical or efficient. If your house has been left cold, a longer warm-up is not the same as using more power than if it had been kept warm all day.
Another myth is that turning the thermostat up higher makes the house warm faster. In most simple systems, the boiler or heater runs at the same output until the target is reached, so a higher setting just overshoots. Pick the temperature you want.
How the three fit together
Think of the controls as layers.
- Pick sensible setpoints for the rooms you use, perhaps slightly warmer for living areas and cooler for bedrooms, but never so low that damp or health becomes a concern.
- Use zones to avoid heating rooms that are rarely occupied.
- Add a schedule that matches your routine, with enough warm-up time.
- Review after a few weeks. If people are constantly using the boost button or opening windows, adjust the settings.
Controls do not change how fast a house loses heat. If a room is cold because of poor home insulation or gaps, a better schedule only moves the problem around. Controls and fabric improvements work together, and checking your energy meter readings over time helps you see whether a change has made any difference.
A note on smart devices
Smart thermostats and radiator valves add convenience, remote control and sometimes helpful reports. Their energy benefit depends on how they are used, and they add standby power use of their own, which is small but not zero. A simple, well-understood schedule can do much the same job.
Results vary between homes, so treat these ideas as a starting point for experimenting with your own settings.