A before-winter routine for your boiler

Why check before winter

A heating system that has hardly run since spring can hide a problem all summer. Air gathers in the radiators, the pressure creeps down and a valve sticks. You only find out when you need the heat.

Pick a mild day, turn the thermostat up and let the heating run for an hour. Then go through the list below. If something’s wrong, you’ve found it with time to spare.

When was it last serviced?

Look for the date of the last service: a sticker on the boiler, an invoice or your maintenance contract. Then check the interval in the boiler’s manual.

Intervals differ. Intergas says at least once every two years, and the installer can adjust that to how much the boiler runs. Milieu Centraal says an older boiler needs cleaning and checking every year, and a modern one every two years in agreement with your installer.

The Rijksoverheid (Dutch government) advises having a gas appliance checked at least once every two years by a CO-vrij certified company. It also points out that doing your own work on one is against the law. My guide to CO certification explains how to check the company doing the work. If yours is due, book a boiler service before the cold arrives.

Bleed the radiators

With the heating on, feel every radiator. One that’s cold at the top has air in it. Bleed it, then check the pressure, because bleeding lowers it.

My guide to radiators that won’t heat up has the steps. It also covers radiators that stay cold for other reasons, such as a thermostatic valve that stuck over the summer.

Check the pressure

Read the gauge with the system cold. Intergas gives 1 to 2 bar; your manual has the figure for your boiler. Milieu Centraal suggests checking it a few times a year, not only before winter.

If it’s low, top it up through the vulkraan (filling valve). The guide to boiler pressure and fault codes walks you through that, and explains what it means when the pressure keeps dropping.

Set the thermostat programme

Check the time and day on the thermostat, especially after a power cut. Put fresh batteries in a wireless one now, rather than on a cold night. Then look at the programme itself.

For a boiler with ordinary radiators, Milieu Centraal suggests 19 degrees when you’re home, 15 when you’re out for a few hours, and 15 from an hour before bed. Adjust it to what feels comfortable.

Turn the thermostatic valves back up on radiators you closed for the summer. Leave the radiators in the room with the thermostat fully open.

Protect exposed pipes from frost

Pipes in an unheated attic, a kruipruimte (crawl space), a garage or along an outside wall are the ones at risk. The water company PWN advises you to:

• wrap the water meter in a blanket or newspaper if it’s in a cold spot
• keep the radiators open and the thermostat no lower than 15 degrees at night and when you’re out, if the meter is indoors
• drain the buitenkraan (outside tap)
• drain the water pipes if you’re away for a few weeks

Insulating pipes in cold spaces, which Milieu Centraal recommends to save energy, also slows them freezing. Many modern boilers have a frost protection setting, but it only works with power and pressure; check your manual.

If a pipe does freeze, PWN says a hairdryer can sometimes thaw it. Never use an open flame. PWN also notes that a meter broken by frost is yours to pay for.

Test your CO alarm

A boiler that isn’t burning properly can produce carbon monoxide, which you can’t see or smell. The Rijksoverheid advises hanging a CO alarm. Press the test button now, and replace the alarm if it has passed the end date printed on it.

Where it hangs matters. In the room with the boiler, the fire service advises the ceiling, 1 to 3 metres from the boiler, central in the room and at least 30 centimetres from the walls. In bedrooms it goes at the height you sleep at. If the alarm’s own manual says otherwise, contact its supplier.

Book what the check turned up

Send me a message on WhatsApp with a photo of the boiler’s type plate, when it was last serviced, and your postcode. A service is €145 incl. BTW plus materials.

Found a fault? My rate is €114.95 incl. BTW per hour, with no call-out charge, and boiler repair explains how a visit works. A room that never gets warm enough may need a different radiator; see radiators.

If you smell gas, leave the property and call 0800 9009 from outside. If a CO alarm goes off or you suspect carbon monoxide, get everyone outside and call 112.