Boiler breakdown: 6 checks before calling a repair engineer

No heating, no hot water? Before calling a repair engineer, a few simple checks can sometimes get the boiler going again — or at least help the technician reach the right diagnosis faster.

1. The power supply

Check that the boiler is powered: display on, fuse or circuit breaker in place, plug connected. A simple power cut is enough to stop the appliance, and some boilers do not restart on their own.

2. The water pressure

Look at the pressure gauge. When cold, the pressure should generally be between 1 and 1.5 bar. Below that, the boiler locks out. Our article on low boiler pressure explains how to restore it step by step.

3. The thermostat

Flat batteries, holiday mode on, set temperature too low, shifted time schedule: the room thermostat is a very common cause of a "false breakdown". Raise the set temperature by a few degrees and listen for the boiler starting.

4. The gas supply or the oil level

Is the gas tap open? Do your other gas appliances (cooker) work? If you have a prepayment meter, is it topped up? For an oil boiler, simply check the tank level.

5. The fault code

Write down the code shown on the display (for example F22, F28, F75…): it is the most useful information for the engineer. See our guide to boiler fault codes. You may try one single reset with the reset button. If the boiler faults again, do not insist.

6. The radiators

If only some radiators stay cold, it may be air in the circuit — in which case you just need to bleed the radiators — or a stuck thermostatic valve, not a boiler breakdown.

When should you call a professional?

• The boiler faults again after a reset.
• The pressure drops again a few days after topping up.
• You notice a water leak under the appliance.
• The boiler makes unusual noises (banging, whistling, a "boom" on ignition).
• You have heating but no hot water, or the other way round.

Never open the casing and never touch the gas circuit: this work is reserved for an approved technician.

Our boiler repair service

A-Heating attends within 24 to 48 hours in Brussels and Wallonia (Liège, Namur, Charleroi, Mons, Walloon Brabant, Hainaut), on all brands: Vaillant, Bulex, Viessmann, Junkers, Bosch, Buderus, Remeha, De Dietrich, Saunier Duval… The repair call-out is €119 incl. VAT (travel and labour); if a part is needed, you receive a quote on site before any repair.