Is It Cheaper to Leave the Heating on All Day?
For a home heated by a gas, oil or LPG boiler, leaving the heating on continuously is not normally the cheapest approach.
A building loses heat whenever it is warmer inside than outside. Keeping it warm throughout the day usually means replacing that lost heat continuously, including during periods when nobody needs the rooms to be warm.
Using a timer and thermostat to heat the home when required is generally more efficient. However, heat pumps work differently and often perform better when maintaining a steady temperature for longer periods.
Why does a warm home keep losing heat?
Heat moves from warmer areas towards colder ones. In a heated home, it escapes through the roof, walls, windows, floor, ventilation and uncontrolled draughts.
The larger the difference between the indoor and outdoor temperatures, the faster heat can be lost.
Turning the heating off or reducing the target temperature when warmth is not needed allows the home to cool. As that temperature difference becomes smaller, the rate of heat loss also falls.
The boiler will use energy when reheating the property, but it is not usually replacing more heat than would have been lost by maintaining the higher temperature throughout the entire period.
What does the room thermostat do?
The thermostat does not normally keep the boiler running continuously.
It measures the temperature around it and asks the heating system to operate when the room falls below the selected level. Once the target is reached, the boiler switches off until the room cools again.
Setting the thermostat higher will not make most homes warm up faster. It simply asks the system to continue heating until it reaches a higher temperature.
Energy Saving Trust recommends using the lowest temperature that remains comfortable. For many people, this is between 18°C and 21°C, although individual needs differ. Energy Saving Trust
Older people, young children and anyone with a health condition affected by cold may require a warmer home or professional health advice.
How should you use a heating timer?
A timer or programmer controls when heating is available.
For a boiler system, set it around the household’s routine rather than automatically running it all day. Common periods include shortly before getting up and before returning home.
Energy Saving Trust suggests setting boiler heating to start roughly half an hour before waking and stop around half an hour before bedtime. The most suitable timing depends on how quickly the particular home warms and cools. Energy Saving Trust
Experiment with the start time instead of setting a much higher temperature. A well-insulated home may warm quickly and retain heat for longer, while an older or poorly insulated property may need an earlier start.
Check the programmer’s clock after power cuts and when the clocks change.
Should the heating be switched off overnight?
Many boiler-heated homes do not need to remain at their full daytime temperature overnight.
A lower overnight setting or an off period can reduce consumption. However, completely unheated rooms may become very cold in poorly insulated or damp properties.
Some households may need background heating because of:
- Health requirements
- Babies or older occupants
- Risk of frozen pipes
- Existing condensation or damp
- Particularly cold weather
- Shift work or overnight occupancy
The appropriate setting depends on the building and the people living in it. The aim is controlled heating, not allowing the property to become unsafe or uncomfortably cold.
Heat pumps need a different approach
A heat pump normally delivers heat at a lower temperature than a traditional boiler and works most efficiently when operating steadily.
Repeatedly switching it off and then asking it to heat a cold property quickly may require higher flow temperatures or more intensive operation. This can reduce efficiency.
Energy Saving Trust advises that heat pumps can be more economical when left operating across the day, using a steady target temperature and a smaller reduction when less heat is required. Energy Saving Trust
This does not mean every heat-pump home should use identical settings. Controls, insulation, radiator or underfloor-heating design and electricity tariffs all matter.
Follow the installer’s commissioning guidance before copying advice intended for a boiler.
What about smart thermostats?
A smart thermostat can make scheduling easier and may provide remote control, multiple heating periods or automatic adjustments.
It does not remove the need for sensible settings. A poorly chosen schedule can still heat an empty home unnecessarily.
Useful features may include:
- Separate weekday and weekend schedules
- Away mode
- Frost protection
- Room-by-room control
- Weather compensation
- Learning how long the property takes to warm
Check that automatic settings reflect the household’s actual routine. Location services and learning functions may not work well for every household, particularly where several people keep different schedules.
Do thermostatic radiator valves help?
Thermostatic radiator valves control the temperature around individual radiators.
They can keep frequently used rooms warmer while reducing heat in spare bedrooms and other less-used areas. A higher number does not make a radiator heat more quickly; it asks the valve to maintain a higher room temperature.
Avoid turning every radiator off without considering condensation, pipework and how the heating system was designed. Some background heat may be appropriate in unused rooms.
Keep curtains and furniture away from valves and the main thermostat so they can sense the room temperature accurately.
Insulation changes how heating should be scheduled
Two similar heating systems can behave very differently in different properties.
A well-insulated home may retain useful warmth long after the boiler stops. A home with limited insulation and uncontrolled draughts may cool much faster.
If the property loses heat quickly, investigate measures such as:
- Loft insulation
- Appropriate wall or floor insulation
- Draught proofing
- Heating-control improvements
- Window and door repairs
Do not block designed ventilation. Ventilation remains important for indoor air quality and moisture control.
Find the setting that suits the home
A useful approach is to change one setting at a time and observe the result for several days.
Record:
- Heating start and stop times
- Thermostat temperature
- Comfort in different rooms
- Daily gas or electricity consumption
- Outdoor weather conditions
Comparing energy use across very different weather can be misleading. A colder week may require more energy even when the controls are being used more effectively.
Leaving boiler heating on all day normally uses more energy than scheduling it around the times warmth is needed.
Use the timer, thermostat and radiator valves together. Start with the lowest comfortable temperature and adjust the schedule according to how quickly the home heats and cools.
Heat pumps are different and often work better with longer, steadier operation. Advice should therefore match the heating technology rather than treating every system in the same way.
