10 Things to Check Before Turning On Your Heating for the First Time This Winter (UK)

The first cold morning of autumn is not the day you want to discover your boiler won’t fire. Here’s a practical checklist you can work through in an hour, in the order that gets the most important things covered first.

1. Book the annual boiler service (if you haven’t)

Manufacturer warranties usually require an annual service by a Gas Safe registered engineer to remain valid. Gas Safe Register’s landlord guidance also requires an annual gas safety check on all gas appliances and flues, with a Landlord Gas Safety Record kept for at least two years. Even if you’re an owner-occupier and not a landlord, the annual service is what keeps small problems small. Book it in September or early October, before every engineer in the country is fully booked.

2. Test your carbon monoxide alarm

An audible carbon monoxide alarm near every fuel-burning appliance is a basic safety measure. Press the test button. If it doesn’t chirp, replace the battery. If it’s over 5–7 years old, replace the whole unit — sensors have a shelf life.

3. Turn the heating on for 10 minutes now

Not to warm the house — to find the problems. On a mild day, put the heating on for 10 minutes. Walk around and check every radiator: does each one warm up? Are any cold at the top and warm at the bottom (trapped air)? Any leaks around the valves? Any funny smells? Our why heating smells of burning guide covers what’s normal and what isn’t.

4. Bleed the radiators

Cold-at-the-top, warm-at-the-bottom means trapped air. Bleeding takes minutes with a radiator key. Do the downstairs ones first, then upstairs. Our bleed a radiator guide walks through it.

5. Check the system pressure

Most modern combi boilers show a pressure gauge on the front. When cold, it should sit between around 1.0 and 1.5 bar (check your manual for the exact range). Too low and the boiler won’t fire; too high and it locks out. If it’s low, top it up via the filling loop, then bleed the radiators, then top up again if needed. If it keeps dropping, book an engineer.

6. Test the timer and thermostat

Set the timer to a period you don’t need heat, then override manually to check the boiler fires. Now set the thermostat above and below room temperature and confirm the boiler follows. If your thermostat is battery-powered, replace the batteries in autumn.

7. Move the furniture off the radiators

A sofa across a radiator absorbs the heat and blocks the convection current. Our things making your house colder guide has this on its list — it’s one of the most common reasons a room doesn’t warm up.

8. Check every TRV turns

Thermostatic radiator valves seize in summer, when nothing calls for heat. Twist each one from off to hot and back. If any are stuck, gently work them free with an adjustable spanner on the shaft (not the head), or call an engineer if you’re not comfortable. A seized-open TRV heats a room to 25°C for no reason; a seized-shut TRV leaves a room cold no matter what the thermostat says.

9. Look at the flue and boiler outside

Walk outside and check the flue outlet is clear (no leaves, nests or covers), and the condensate pipe running down to the drain is intact and insulated where it’s exposed. A frozen condensate pipe is one of the most common winter breakdowns — see our condensate pipe guide.

10. Lag the pipes and stock the kit

Finally, do the winter-proofing your future self will thank you for: lag exposed pipes (see our pipe lagging guide), fit an outside tap cover, top up the salt in the salt bin if you have one, dig out the kettle-and-torch power cut kit, and know where your stop tap is.

Frequently asked questions

Sources

• Gas Safe Register — Landlord gas responsibilities
• Energy Saving Trust — Thermostats and heating controls

Related reading: our how to bleed a radiator, pipe lagging guide and frozen condensate pipe guide.