Getting your heating ready for winter: a maintenance checklist

Why the months before winter matter

Most heating faults start during the long summer break, not in winter. A circulation pump that has not turned for months can stick. Valves and thermostatic radiator heads can seize in one position. Air works its way into the system, and pressure slowly drops through a weeping joint that nobody notices while the heating is off.

None of this shows until you switch the heating on. If you find it in October, it is a simple fix on a day of your choosing. If you find it on the first cold night, you wait in the cold, at the same time as everyone else who put it off.

Step 1: a test run in October

Pick a mild day and run the heating for an hour or two, with every radiator valve and every underfloor zone open. Walk through the house while it runs.

You are looking for four things: every radiator and heated floor getting warm, no new noises from the boiler, pump or pipes, no drips at radiator valves, the boiler or the manifold, and pressure on the boiler gauge that stays steady once the system is hot.

If everything warms up and stays quiet, the system has come through the summer well. If something is off, note which room and what you noticed. It saves time when you call.

Step 2: check the boiler pressure

Most boilers in sealed central heating systems have a pressure gauge on the front or underneath. For the systems we install, the system pressure should sit between 2 and 3 bar. Your boiler’s own range is also marked on the gauge or in the manual.

If the pressure is well below the marked range, the boiler may refuse to fire. If you know where the filling loop is and the manual explains how to top up, you can bring it back to the marked level. If it drops again within days, there is a leak or a faulty part somewhere, and topping up again only hides it.

If the pressure is too high, or the relief valve outside the house is dripping, switch the boiler off and call a technician rather than draining water yourself.

Step 3: bleed radiators that are cold at the top

A radiator that is warm at the bottom and cold at the top has air trapped inside. Bleeding lets it out. You need a radiator key, which fits the small valve at the top corner, and a cloth.

Switch the heating off and let the radiators cool, so you are not releasing hot water. Hold the cloth under the valve, turn the key a quarter turn and you will hear air hiss out. Close it as soon as water starts to come out. Then check the boiler pressure again, because bleeding lowers it, and top up if needed.

Start with the radiators on the lowest floor and work upwards. If the same radiator needs bleeding every few weeks, air is getting in somewhere and the system needs checking.

Step 4: thermostats, controls and clear space

Replace the batteries in wireless room thermostats, even if they still work. Check the date and time, and that each schedule matches how the house is used this year. Smart thermostats may need their app updated or reconnected to Wi-Fi after the summer.

Turn each thermostatic radiator valve from minimum to maximum and back a few times, so it does not stay stuck. Move sofas, beds and long curtains away from radiators, and keep rugs and furniture without legs off heated floors where you can.

Underfloor heating, heat pumps and hot water

With underfloor heating, look at the manifold during the test run. Each loop has a flow meter or indicator, and every zone should show flow when its thermostat calls for heat. A zone that stays cold usually points to an actuator or a thermostat rather than the pipes in the floor.

A heat pump sits outside, so dust, sand and leaves collect on the outdoor unit over summer. Clear anything blocking the airflow around it and keep plants and stored items well back. Cleaning the coil itself and checking the refrigerant side is a job for a technician.

Hard water leaves scale inside boilers, hot water cylinders and heat exchangers, which slowly cuts efficiency. If your hot water has become slower to heat or the boiler has grown noisier, scale is a likely cause and a service will deal with it.

Gas boilers: safety first

A gas boiler needs a clear flue and good ventilation to burn safely. Never block the flue outlet or the air vents in the room where the boiler is, and do not store things against the boiler. Yellow or orange flames instead of blue, soot marks around the boiler, or a pilot light that keeps going out all need a technician before the boiler is used.

If you smell gas, do not switch lights or appliances on or off and do not use a flame. Open the windows, turn off the gas at the meter valve, leave the home and call the gas emergency line from outside.

Headaches, dizziness or drowsiness that ease when you leave the house can be a sign of carbon monoxide from a faulty appliance. Switch the boiler off, air the home and have it checked. A carbon monoxide alarm near a gas boiler is an inexpensive safeguard.

What a professional service covers

The checks above catch the obvious problems. A service goes further: the boiler or heat pump is opened, cleaned and tested, the burner and flue are checked on gas boilers, and safety devices such as the pressure relief valve and expansion vessel are tested.

The technician also checks the water in the system, the pump and valves, balances the radiators so each one gets its share of heat, checks the underfloor manifold and actuators, sets up the thermostats, and replaces any worn parts. Once a year, before winter, is the usual rhythm.

Yourself or a technician?