Boiler Switch On Day: The five-minute checklist homeowners should complete before switching on their heating

As temperatures begin to fall across the UK, millions of households are preparing to switch their central heating back on for the colder months. With the unofficial ‘Boiler Switch On Day’ typically falling on the third Monday in October (19th October this year), homeowners are being urged to make five simple checks before reaching for the thermostat.

The warning comes as households face higher gas unit prices starting in October 2026, making it even more important to check that heating systems are running efficiently.

Chris Jessop, heating expert at Ideal Heating, is encouraging homeowners to spend a few minutes checking their heating systems, so they can spot potential problems before the coldest weather arrives.

Chris explains: “After months of little or no use, it’s worth giving your heating system a quick check before switching it back on. Small things like low boiler pressure, incorrect thermostat settings, or an unnoticed leak can easily be overlooked during the warmer months.

“Making a few simple checks now can help you identify potential issues early, rather than discovering something isn’t working properly when you’re relying on your heating every day.”

Check your boiler pressure
One of the quickest checks homeowners can make before switching on their heating is to check their boiler pressure gauge.

When your heating is running, the water inside expands, and it’s normal for the pressure to rise slightly. It should increase by around 0.5 bar, so it might sit closer to 2 bar while active.

When the heating is off, your boiler pressure gauge should read between 1 and 1.5 bar, with a green zone indicating this. If your pressure drops below 1 bar when the system is cold, you may need to take action. Always consult your boiler’s instructions before attempting to adjust the pressure.

If your boiler pressure drops, the system won’t work properly because the pressure won’t be at the required level to pump water through the boiler. Low boiler pressure causes your boiler to work harder to heat your home, increasing energy use and potentially increasing your energy bills.

Check your thermostat settings and batteries
Before switching your heating back on, take a moment to check that your thermostat is working correctly and that its settings still match your household’s routine.

After several months of warmer weather, heating schedules may no longer reflect when you’re waking up, leaving the house or returning home.

If you have a wireless thermostat, check whether the batteries need replacing and make sure it’s communicating with your boiler. For programmable thermostats, review the heating schedule and temperature settings before switching the system back on.

With the clocks going back on 25 October 2026, it’s also worth checking whether your heating controls update automatically, as some older programmers may need to be adjusted manually.

Taking a few minutes to review your settings can help ensure your heating comes on when you actually need it, rather than following an outdated schedule.

Check if you need to bleed your radiators
Once you’ve switched the heating on for an initial test, carefully check whether your radiators are warming evenly. If a radiator remains cold at the top but warm at the bottom, trapped air may be preventing it from heating properly.

To bleed the radiator yourself, switch off the heating and allow it to cool first. Open the bleed valve slowly, listen for air escaping, and close it as soon as water emerges.

This also applies to new-build homes, even if you’ve just moved in, as air can become trapped between installation and completion. After bleeding your radiators, check your boiler pressure again, as releasing trapped air can cause the pressure to drop.

Find your ‘ideal room temperature’
It’s not uncommon to acclimate to the temperature in your home, but the range of ‘comfort’ is surprisingly small – it’s about 18–21 °C for the average living room. However, this can change depending on factors such as your age, your activity levels, and the ventilation in your home.

Finding your ideal temperature can save money on your energy bills in the long run. Experiment with different temperatures to see what works best for you, as you may find that you don’t need to sit at 21 °C or above, and that cooler temperatures better suit your lifestyle.

Schedule a service with a Gas Safe Engineer
Understanding how to maintain, improve, and optimise boiler efficiency is essential knowledge for every homeowner, and the most important measure you can take is to schedule your annual service.

Not only does an annual service maintain your boiler’s warranty, but the engineer will also clean all the parts and components in your boiler and ensure they are in good working order. This will prepare your system for more frequent use and identify any underlying issues, so you’re not left with a faulty boiler during the coldest months of the year.