When to Turn the Heating On, and What to Check First
There's no official date to put the heating on in the UK. How to decide by temperature rather than the calendar, the checks to do before the first cold night, and what it means if the heating won't come on after summer.
There's no official date to put the heating on in the UK. Go by temperature, not the calendar: turn it on when the rooms you use regularly drop below a comfortable level, and UK health guidance suggests keeping them at 18°C or more for older people and anyone with a health condition. For most homes that is some time between late September and October. Before the first cold night, run the heating for half an hour, check the boiler pressure, bleed any radiators that are cold at the top and reset the timer.
Key Takeaways
- Decide by room temperature, not by date. 18°C is the widely used guide for rooms you use, especially for vulnerable people.
- Test the heating on a mild day before you need it, so a fault isn't discovered on the first cold night.
- Check boiler pressure, bleed radiators and set the timer before the season starts.
- The clocks go back on 25 October 2026. Check any timer that doesn't adjust itself.
- A boiler that won't fire, radiators cold at the bottom or new noises after summer need looking at before the weather turns.
There is no official date to put the heating on in the UK. The sensible rule is to turn it on when the rooms you use regularly drop below a comfortable temperature, and UK health guidance suggests keeping them at 18°C or more for older people, babies and anyone with a health condition. For most London homes that point arrives somewhere between late September and October. Whatever the date, give the system a test run on a mild day first, because a boiler that has sat idle all summer is more likely to show a fault the first time it's asked to work hard.
When to put the heating on
People often wait for a particular date, or hold out until the first properly cold week. Neither is a good guide. What matters is the temperature indoors, and that varies a lot between a top-floor flat in a modern block and a Victorian terrace with single glazing.
A practical approach:
- Get a cheap room thermometer for the living room and main bedroom, rather than relying on how you feel after walking in from outside.
- Use 18°C as the guide for rooms you use, particularly bedrooms at night if anyone in the house is elderly, very young or unwell. The UK government's cold weather advice says the same.
- Watch for condensation and damp. A cold house with washing drying indoors gets condensation on windows and walls. Some background heat helps keep that under control.
- Think about the pipes, not just people. Any home that could drop close to freezing, including an empty flat or a holiday let, needs at least frost protection once nights turn cold. See our advice on preventing frozen pipes.
Test it before you need it
The worst time to find a heating fault is on the first genuinely cold evening, when many other households are finding the same thing. Pumps and diverter valves that haven't moved since spring can stick, pressure can have crept down over the summer, and timers can lose their settings.
Pick a mild day in late September or early October. Turn the room thermostat up a few degrees above room temperature, set the timer or programmer to on, and let the heating run for 30 to 60 minutes. Walk round every radiator. They should all be warm across their whole surface, and the boiler should run without new noises or fault lights. If something isn't right, you have time to sort it before you depend on it.
Pre-season heating checklist
Check the boiler pressure
On a sealed system (most combi and system boilers) the gauge should read about 1 to 1.5 bar when the system is cold. Below 1 bar, top it up through the filling loop. Our guide on how to repressurise a boiler takes you through it.
Feel every radiator
Cold at the top and warm at the bottom means trapped air, so bleed it. Warm at the top and cold at the bottom usually means sludge. One radiator cold all over can be a stuck TRV pin. See why a radiator won't heat up.
Set the timer and thermostat
Replace batteries in wireless thermostats, check the programmer's clock and set heating times for the season. The clocks go back on 25 October 2026, so check any timer that doesn't adjust itself.
Check the condensate pipe
The plastic pipe that runs from a condensing boiler to a drain can freeze in cold snaps and stop the boiler. Make sure the outside section isn't cracked or blocked, and read our guide to a frozen condensate pipe or blocked flue.
Test the carbon monoxide alarm
Press the test button on the CO alarm near the boiler and any other gas or solid fuel appliance. Replace it if it's past its expiry date.
Check when the boiler was last serviced
Manufacturers recommend an annual service, and it's usually a condition of the warranty. Booking before the cold weather is easier than in the middle of it. See our boiler service.
Common problems at first switch-on
- Boiler won't fire or shows a fault. Note the code, check the pressure and gas supply, then try one reset. Our guide on how to reset a boiler explains what to check first and when to stop.
- Hot water works but no heating. This often points to the controls or a diverter or zone valve that has stuck over summer. Read why central heating stops working.
- Radiators heating unevenly. Some scorching, others lukewarm, even after bleeding, means the system needs balancing with the lockshield valves. See what a lockshield valve does.
- Banging, gurgling or kettling noises. Air, sludge or scale in the heat exchanger. A little gurgling right after bleeding is normal. Persistent noise isn't. See our guide to a noisy boiler.
- Pressure dropping every few days. There's a leak somewhere or the pressure relief valve is letting water go. A leak that stayed hidden all summer shows up once the system is hot and expanding.
Timer, thermostat and running costs
For most homes, heating the house when you need it on a timer uses less energy than leaving it on low all day, because a warm house loses heat to the outside the whole time it is warm. Set the heating to come on about half an hour before you get up or get home, and to go off a little before you go to bed or leave.
Use TRVs to keep spare rooms cooler, and keep the room thermostat in a room you use, away from radiators, direct sun and draughts. Turning the thermostat up higher does not heat the house faster. It just keeps it running longer once you're warm. If your controls are old or awkward to use, our smart thermostat installation and heating controls pages explain the options.
If you're going away for more than a night or two once the weather turns cold, leave the heating on a low setting or the boiler's frost protection mode rather than switching it off completely. A burst pipe in an empty home costs far more than the gas.
When to call an engineer
Call a Gas Safe registered engineer if the boiler shows a fault code that comes back after a reset, keeps losing pressure, makes new noises, or if radiators stay cold after bleeding. Early autumn is the best time to get a fault fixed, before a cold snap brings a rush of breakdowns. Our central heating repair and boiler repair pages cover what we do, and if you have no heating at all, see no heating.
Our labour is £95 an hour, the £60 call-out is waived when the job runs over 2 hours, and we confirm the price before any work starts.
Heating not right after summer?
Tell us the boiler make, the fault code if there is one and what the radiators are doing. We'll confirm the price before starting.
📞 Call 020 7870 3200Or see our heating repairs and pricing.
Frequently Asked Questions
What month should you turn the heating on in the UK?
There's no set month. Most households start using the heating at some point between late September and October, but it depends on the weather, how well your home holds heat and who lives there. Go by the temperature of the rooms you use rather than the date.
What temperature should my house be before I turn the heating on?
UK health guidance suggests heating the rooms you use to at least 18°C, particularly for older people, babies and anyone with a long-term health condition. If living rooms or bedrooms are regularly falling below that, it's time to put the heating on.
Is it cheaper to leave the heating on low all day?
For most homes, no. A house loses heat all the time it is warmer than outside, so keeping it warm when nobody needs it uses more energy overall. Heating it on a timer for the times you are in is usually cheaper. The exception is frost protection when you're away, which is about protecting pipes rather than comfort.
Should I bleed my radiators before turning the heating on?
Only if they need it. Turn the heating on first and feel each radiator once it's warmed up. If one is cold at the top and warm at the bottom, turn the heating off, let it cool and bleed it. Then check the boiler pressure, because bleeding lowers it.
Why won't my heating come on after summer?
The common reasons are a timer that lost its settings, a room thermostat with flat batteries, low boiler pressure, a pump or diverter valve that has stuck after months of not moving, or a boiler that has locked out. Check the controls and pressure first. If the boiler shows a fault code or locks out again after a reset, call a Gas Safe engineer.
Sources and further reading
Source links checked 27 September 2026. Scheme rules and manufacturer instructions can change; use the current official guidance for your account or exact appliance.