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Inverness

Plumbers Arms member
Plumber
Gas Engineer
Jul 28, 2013
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Member Type
General Plumber
hi guys. Went to a breakdown today. Fault code suggested flame failure check gas supply. I cracked open the nut to the gas isolation at the boiler good flow of gas.. the inlet on the gas valve very small amount of gas creeping out. Would I correct in saying new multifunction gas valve required?
 
Not necessarily, most gas valves have a mesh filter built into the inlet of the valve.
It may be worth undoing the closest connection on the inlet side of the valve, or removing the gas valve, to check if the filter is clogged.
 
I've ordered a new gas valve so I'll replace it. Thanks
 
Simple test

Manometer on inlet test point of boiler

Shut boiler ISO for gas off

Turn on call for boiler eg demand

Does the pressure drop on manometer ?

If it doesn't open and boiler is sparking gas valve at fault

If it drops and boiler is sparking not gas valve fault
 
Check gas supply Low gas pressure, Check gas service cock open, Check gas valve and lead, Check detection electrode/lead No flame signal on ignition, or loss, Check gas supply of signal during operation, Check gas valve and lead attempts, Check PCB gas valve connectors, Check mains earth lead continuity, Check Flue gas temperature sensor. It could be a few things not necessarily the gas valve. Muti-meter will determine what is not working & possibly it's a PCB fault if everything else checks out.
 
All I did when I attached a u gauge on the inlet the gas slowly travelled up the u guage
 
Also the boiler is working but it's an intermittent fault.
 
I didn't check. When I opened the gas inlet it wasn't flowing out like it normal does. So I thought I figured out the problem.
 
Had one of these before with same fault. Changed gas valve, sensors, pcb, ended up being the burner was v intermittent. Burner had no signs of damage but that is what solved it in the end. Nightmare boilers
 
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Process of limitation at the customers wallet!,
 
Strange how the gas inlet point was struggling to pass gas through the screw..
 
Electrodes needed cleaned. Now boiler working fine.
 

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