Pressure too low
Below about 1 bar the boiler stops to protect itself. Top up to 1.5 bar when cold; if the pressure drops again quickly, there is a leak.
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Boiler Won't Start: Find the Cause and Fix It
A blank display, a burner that won't light, or a boiler that fires up and stops straight away: these are three different faults. Here is how to tell them apart and what you can check yourself. If it still won't start, a heating engineer comes out 7 days a week.
5,0on Google· 22 years of experience
On-site diagnosisWith test equipment
Gas and oilAll brands
Price given firstBefore any repair
7 days a weekEvenings and weekends
Blank display: the boiler has no power
If the boiler display is completely dark, it is not getting power or its control board has failed. Start with the fused spur or socket next to the boiler, then the breaker that feeds it in the fuse box.
A breaker that trips again as soon as you reset it points to a short circuit: the pump, the fan or a frost protection heater may be to blame. Do not keep trying. After a thunderstorm, the fuse on the control board may also have blown to protect it.
The engineer measures the supply, checks the board fuses and isolates the component causing the short. He replaces the faulty part and checks that the boiler's electrical connection is sound, with a proper earth.
Display on, but the burner won't light
The boiler has power, starts its cycle, the fan runs, but no flame appears and an ignition fault is shown. First check the gas valve is open and your gas hob works: a closed meter or a supply interruption gives exactly this symptom.
If gas is reaching the boiler, the cause is inside it: a worn or badly gapped ignition electrode, a dirty flame sensor, an air pressure switch that does not close, a blocked flue or a gas valve that no longer opens. Each part is tested with a specific instrument.
The engineer measures the gas pressure during ignition, the flame current and the pressure switch operation. He replaces the faulty part, then carries out a combustion analysis to make sure the boiler burns cleanly before he leaves.
Oil boiler: the burner refuses to fire
On an oil boiler, the red light on the burner means a safety lockout. The burner tried to start, saw no flame and locked out. An empty tank is the simplest cause; then come a blocked filter, a dirty nozzle and a sooty photocell.
You can press the reset button once. If the burner locks out again, stop pressing: unburnt oil collects in the combustion chamber and can cause a hard ignition on the next attempt.
The technician checks the oil level and suction, cleans or replaces the filter and nozzle, tests the pump and adjusts the burner. If the tank ran completely dry, he bleeds the line and advises having the filter checked after each delivery for a while.
It starts then stops: common causes
A boiler that fires for a few seconds or minutes before cutting out behaves differently from one that will not start at all. The causes differ.
Overheating
A stuck pump or all radiators closed stop the water circulating. The boiler heats up too fast and locks out.
Poor flue extraction
A blocked flue or a nest in the chimney makes the boiler fault shortly after lighting.
Dirty flame sensor
The flame lights but the boiler does not see it long enough and shuts the gas off. Cleaning is sometimes enough.
Blocked condensate trap
On a condensing boiler, the condensate cannot drain and the boiler stops, especially after frost.
What the engineer does
Listening and code
On the phone you describe what happens and give the code. We prepare the right parts.
Tests and price
On site he tests the power, gas or oil, ignition and flame, then gives the repair price.
Checked repair
He replaces the part, restarts the boiler several times, checks the combustion and hands you the job sheet.
What our customers say
Where do we work?
We repair boilers that won't start anywhere in Belgium: Brussels, Flanders and Wallonia, in houses and flats.
BrusselsWalloon BrabantFlemish BrabantHainautNamur provinceLiège provinceLuxembourg provinceAntwerpEast FlandersWest FlandersLimburg
The brands we work with
Our technicians work on all brands: they install, service and repair appliances from the major manufacturers. For a new installation, we recommend the model that suits your home and budget.
We buy our equipment from all the major Belgian wholesalers and suppliers, including Facq, Van Marcke and Desco: genuine parts, quickly available.
Frequently asked questions
How many times can I reset my boiler?
Once. If it locks out again, the safety device has a real reason to cut out: repeated resets can damage the boiler, especially with oil.
My boiler won't start after a power cut. What now?
Check the breaker and the boiler switch. If the display stays blank, the board fuse may have blown: the engineer checks and replaces it.
The boiler clicks but won't light. Why?
Those are the ignition sparks. If the flame does not catch, gas is not arriving, the electrode is worn or the gas valve no longer opens.
The thermostat calls for heat but the boiler doesn't respond?
The thermostat batteries, its cable or the wireless link may be at fault. The engineer runs the boiler directly, bypassing the thermostat, to see which side the fault is on.
Can you come today?
We offer the first available visit, often the same day depending on your area. Call 0477 03 88 98 to find out the time.
How much does it cost to get the boiler going?
It depends on the part to replace. The engineer gives you the price after the diagnosis and before the repair.
Do you repair older boilers?
Yes, as long as parts are available. If they are not, the engineer tells you and you can ask for a replacement quote.
Boiler still won't start?
Call us, book a slot online or request a quote if you are thinking of replacing it.