Went to this on Friday last week, boiler going to flame failure and no further on both CH and DHW. Fan running, No ignition, checked APS manually and boiler fired straight away.
Replaced APS and still same fault, owner told me there had been a lot of work in that part of the house (its a recently added unfinished extension) and the appliance had been inundated with dust and debris.
Still the boiler would light manually using the APS but on it's own went FF. Dismantled the flue, sec heat ex, and hoovered all out thoroughly, at that point my apprentice snapped the pipe spigot off the venturi so I bought a new one (£5 luckily) and fit the whole lot back together. Boiler fired up all great, job done.
Call today boiler going to FF again, this time on CH and DHW. With either demand it ignites, gas valve modulates ok for about a minute, then boiler knocks off, after about ten secs FF lights then after another ten secs boiler relights. No 'Reset' needed. If the demand is for DHW then when the burner goes off both the pump proving switch and the DHW switch remain ''on''. I'm suspecting something very simple but have checked thermistor, OH stat, Flue stat, all seem to test ok. Not convinced it's still a flue issue but wondering if anyone has experienced this. Flue is about 18" in length and has the flue pluming kit fitted.....Anyone any ideas ??? Thanks in advance.
Just to add, the boiler was moved from one side of the room to the other about six months ago and since the move the owner says it has gone FF now and again, before the move it was fine.
Replaced APS and still same fault, owner told me there had been a lot of work in that part of the house (its a recently added unfinished extension) and the appliance had been inundated with dust and debris.
Still the boiler would light manually using the APS but on it's own went FF. Dismantled the flue, sec heat ex, and hoovered all out thoroughly, at that point my apprentice snapped the pipe spigot off the venturi so I bought a new one (£5 luckily) and fit the whole lot back together. Boiler fired up all great, job done.
Call today boiler going to FF again, this time on CH and DHW. With either demand it ignites, gas valve modulates ok for about a minute, then boiler knocks off, after about ten secs FF lights then after another ten secs boiler relights. No 'Reset' needed. If the demand is for DHW then when the burner goes off both the pump proving switch and the DHW switch remain ''on''. I'm suspecting something very simple but have checked thermistor, OH stat, Flue stat, all seem to test ok. Not convinced it's still a flue issue but wondering if anyone has experienced this. Flue is about 18" in length and has the flue pluming kit fitted.....Anyone any ideas ??? Thanks in advance.
Just to add, the boiler was moved from one side of the room to the other about six months ago and since the move the owner says it has gone FF now and again, before the move it was fine.
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