baxi 105 flame failure light keeps coming on-HELP PLEASE

12 Jan 2011
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United Kingdom
My Baxi 105HE boiler has decided to run for 20 seconds then the flame failure light starts flashing.The boiler was working perfectly untill I switched it off to install a new Kitchen- tap then when I switched the boiler back on this started! could fitting the tap have damaged something ? mabye putting full cold water pressure up the hot water system the wrong way would be gratefully appreciated....cheers Jim
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Hi Jim,

When you say you turned it off was it just the cold water inlet into the boiler/mains stop cock? i.e uve not interfered with the yellow gas cock below the boiler?
if youve just turned off the stopcock the heating at least definitly shouldnt be affected. Is the lockout fault the same length of time with both running the heating or the water?
It may just be a freak thing once your boiler starts to fire it will try a couple of times before going to lockout which will be about the 20 secs you say so im unsure if its actually lighting at all which would point to an ignition/gas problem, nothing to do with the water being off

Hi,I did just turn off the cold water supply and the electricty -not the gas(I dont like touching gas supplies if not necessary)The boiler stays on for the same amount of time no matter if its hot water or central heating,it does light( as I took the front cover off to see in the glass )for mabye 4 or so seconds then goes out.The flame looks "normal -blueish but not yellow,the condensate trap is empty and not blocked -any ideas? I am a time served mech technician in the oil industry (25 yrs )so replacing a part shouldnt be difficult
id like to hear someone else's opinion but id imagine so long as the gas inlet pressure from the meter into the boiler is ok then the rectification problems due to the detection electrode/lead or more than likely the main pcb,quite common to fail on them but id wait to hear from someone else

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Whatever the cause, it is rather unlikely it is suitable for a diy solution; you'll be both quicker and cheaper if you find yourself a boiler repair specialist.
Cheers and thanks for the replies to my problem ,I fixed it-does this make me a boiler repair specialist now!
Well done Jim, what was the matter with it if you dont mind me asking?

Cheers and thanks for the replies to my problem ,I fixed it-does this make me a boiler repair specialist now!
Not really. You made it work, but you have no idea whether it is working safely, correctly, or reliably.
It could have been a safety device preventing the boiler from coming on, and by disabling that making the boiler work. This is the main reason for stating that it was not suitable for diy, which is different from: impossible to diy.
Ray it was a problem with the condensate trap after all! turns out the outside drain was blocked with ice -it had a small hole through it that worked fine for normal drainage etc so this restricted full bore flow- which in turn backed up really fast as I turned the tap on full bung after I fitted it to flush out any rubbish that was in the system so this then stopped the condensate trap system working properly therefore the system system shut down.
Bengasman-working in the oil industry I have a good idea of what is safe and not safe -I work with systems that have pressures of around 30,000 P.S.I.and work on equipment that if it fails could injure hundreds of people and cause MILLIONS of pounds worth of damage .SAFETY IS PARAMOUNT and disabling a safety system would be the work of a cowboy and could never be condoned .Surprisingly I joined this forum to gain Knowledge -which would be very usefull to ensure that I have clue about what I am doing and make sure that what I am doing is SAFE and LEGAL .Just because someone is attempting to D.I.Y. a task does not make them a cowboy! I did try to phone numerous boiler repair specialists but it would be next week at the earliest before someone would even cross my doorstep!-no heat -no hot water four kids -go figure why people join a forum to attemt to find out if its a simple repair.
Jim your very very lucky with that then,
I had onc before christmas with a choked drain so cut it ouside to run away but they'd reset it that much it filtup and rain through the fan which is conneceted to the gas valve. both needed replaced + the burner stripped down cause their co levels were sky high.
Lucky there were on a gasboard service plan and i was just subbying not one of the better jobs :LOL:

Only complaint youl get.. not from me as with the water backing up into the boiler it may have thrown your co ratios which are critical and your boiler might not be burning too clean but i dont think id be caring either's not all thawed out in Fife yet?

Yeah we have almost thawed out here but the acumulated (ahem) stuff that is needed around the garden was "collected" around where the drain was had held a HUGE chunk of icy snow so the temp was well below ambient- once cleared and a few hot kettles around the place all is sorted.I`m not bothered about the co levels as I am going to get a replacement boiler fitted in the summer ( obviously by a trained and gas safe fitter) so as long as it gives heat an hot water and my carbon monoxide monitor in the kitchen does not go off I am happy.cheers Jim
You made a gas fitter look a bit of a dope. It's not illegal to do that - but they think it ought to be. :p

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