When Should I Put the Heating On? (And What Temperature to Set It)
Most UK homes turn the heating on in October, once it’s regularly below about 15°C outside. Set your thermostat somewhere between 18°C and 21°C, and you’ll stay comfortable without wasting energy.
Temperatures across the UK have just dropped below 15°C, and one question is on everyone’s mind: is it time to put the heating on? It’s the debate that starts in homes up and down the country every autumn, so we asked our engineers for their advice: when to switch on, what to set it to, and how to make sure your boiler’s ready for the cold.
When should I put the heating on?
There’s no official date, but the simple rule is this: put the heating on when you start to feel cold. For most homes, that’s once outside temperatures regularly drop to around 15°C or below, which usually happens in October.
That moment has arrived. With temperatures now dipping below 15°C, lots of our customers are switching on this week. If you’re feeling the chill, there’s no need to hold out for a particular date.
If anyone in your home is older, very young or unwell, don’t wait. A cold home can affect health, so keeping warm comes first.
Our tip: set a timer so the heating comes on about 30 minutes before you get up and switches off about 30 minutes before bed. If the house is empty during the day, turn it off while you’re out.
What temperature should my thermostat be?
Aim for between 18°C and 21°C. It’s the sweet spot for a comfortable, healthy home without wasting energy.
- 18°C is the minimum to aim for, especially in bedrooms and for anyone vulnerable to the cold.
- 21°C is plenty for living rooms. Going higher mostly adds to your bill.
- Turning it down by 1°C (say from 22°C to 21°C) can make a noticeable difference to your bills over the winter.
One common mistake: turning the thermostat right up doesn’t heat your home any faster. It just keeps the boiler running for longer once you’ve reached a comfortable temperature. Pick your number and leave it there.
What temperature should my boiler be set at?
Your thermostat and your boiler aren’t the same thing. The thermostat controls how warm your rooms get. The boiler’s flow temperature controls how hot the water is that goes round your radiators.
For central heating (combi boilers): set the radiator dial to around 60°C. Lots of UK boilers are left at 70–80°C, which is hotter than needed. At 60°C, a modern condensing boiler can work as it was designed to and waste less energy. If someone in your home is over 65 or has a health condition, 65°C may suit you better so rooms warm up faster.
For hot water:
- Combi boiler: around 50°C is usually comfortable for taps and showers.
- Hot water cylinder (system or regular boiler): keep the stored water at 60°C. This stops bacteria such as Legionella from growing, so don’t turn it lower.
Not sure which dial is which, or which boiler you have? Every model is a little different, so check your manual or ask one of our Gas Safe engineers to set it up for you at your next service.
Is it cheaper to leave the heating on low all day?
If you have a gas or oil boiler, no. It’s one of the most common heating myths. Keeping your boiler ticking over all day uses more energy than heating your home only when you need it.
The cheapest approach is simple:
- Use a timer or programmer so the heating comes on when you’re home and awake.
- Set your thermostat between 18°C and 21°C.
- Use thermostatic radiator valves (TRVs) to turn down rooms you don’t use much, like spare bedrooms.
If you have a heat pump, the advice is a little different, so have a chat with our team.
Check your boiler pressure before the cold sets in
Before you switch on for the first time, take a quick look at the pressure gauge on the front of your boiler. With the heating off, most boilers should sit between 1 and 1.5 bar. It’s normal for it to rise a little while the heating’s running.
- Too low (under 1 bar): your heating may not work properly or the boiler may lock out. Many boilers can be topped up using the filling loop, and your manual will show you how.
- Too high (over 2.5 bar when cold): this can put strain on the system. Bleeding a radiator can bring it down.
- Keeps dropping? That can point to a leak. Give us a call rather than topping it up again and again.
Cold radiators at the top usually mean trapped air, so it’s worth bleeding them before winter too.
Get your boiler serviced before the first cold snap
Now the cold has arrived, boilers that have sat idle all summer are being asked to work hard again, and this is when small problems tend to show up. An annual service is the easiest way to catch small issues before they turn into a breakdown on the coldest night of the year.
A service helps to:
- keep your boiler running safely and efficiently
- spot worn parts early, before they fail
- keep your manufacturer’s warranty valid
Our Gas Safe engineers have been looking after homes across the Midlands and South West since 1980. Want peace of mind all year round? Our Care Plans start from £12.50 a month and cover repairs up to £500. One of our engineers will visit to check your system before cover begins.
Book your boiler service today. Call us on 0330 383 0000 or visit customheat.co.uk.
