Grant 90 V3 boiler single bang while firing up

Hello Guys,

I have bought my Grant 90 VE boiler four years ago. All well until last night, but the early morning I have observed that boiler made a single bang while firing up. I tried every possible thing but nothing works. Someone, please help me.

Thanks in advance


Hi James,

If your grant boiler is making a single bang while firing up then, it is possibly due to a delayed ignition. When the gas boiler gets a call for immediate heat throughout the normal operation, a gas valve of the boiler opens & discharges a small quantity of gas into the sealed combustion chamber through small jets. After this gas is ignited by, a pilot light & the flame of jet heat up the heat exchanger. The boiler uses this heat exchanger in order to heat water. However, in your case, gas, which is sent into a combustion chamber, does not ignite instantly. As a result, gas builds & builds inside a combustion chamber up until bang. Eventually, pilot light ignites all the gas thus causing a small explosion. I would suggest you call an expert boiler engineer immediately.