Boiler will not fire up at all: power, demand and safety chain
Nothing at all from the boiler is usually better news than a dramatic fault code. Dead appliances are frequently power or control problems rather than mechanical failures.
The engineering behind a boiler that will not fire
Check the fused spur and the consumer unit first, then confirm the programmer is actually calling for heat and the room thermostat is set above room temperature. Wireless thermostats with flat batteries are a genuinely common cause. If power and demand are both present, the safety chain — overheat stat, condensate float, pressure switch — is holding the appliance off and needs testing.
Who should undertake the work
- Gas appliance work must be completed by a suitably qualified Gas Safe engineer
- Oil appliance work should be completed by a suitably qualified OFTEC technician
- Jamie Crawford Heating states both Gas Safe and OFTEC registration
Key points on a boiler that will not fire
- Wireless thermostat batteries are a leading false alarm
- Check the fused spur switch, not just the consumer unit
- A tripped RCD often points at another appliance entirely
- No display at all is electrical until proven otherwise
- Smart thermostat pairing loss behaves exactly like a dead boiler
Questions we get asked
- Boiler is dead but other sockets work — what now?
- Check the dedicated fused spur near the boiler and its fuse. That circuit is separate from your socket ring.
- Could it be the PCB?
- It can be, but PCBs are the last thing to condemn, after supply, demand and safety devices are proven.
Related help pages
- Baxi fault codeBaxi E119: low system pressure on a Baxi combi
- Glow-worm fault codeGlow-worm F75: pressure sensor and pump communication fault
- Fuel qualitySludge and water in an oil tank: symptoms and remedies
- Alpha fault codeAlpha E1: ignition lockout on an Alpha combi boiler
- Oil boiler comparisonInternal vs external oil boilers: which suits your property
- Comparing quotesWhy quotes for the same job can differ between engineers
Where we deal with this
Need help with a boiler that will not fire?
Where this leaves you: Power, demand, safety chain, in that order. Most dead boilers are back on before anyone opens the casing.
Jamie Crawford Heating is based at 24 Bristol Road, Radstock, BA3 3EE.
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