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Central Heating

Pilot light intermittently switches on and off while running hot water

Anonymous user 16/03/2024 - 2.47 PM

Hi there, can anyone advise me, my shower runs boiling hot to luke warm, while observing the boiler I notice the pilot light flicks off and on intermittently, obviously hot when it fires up, luke warm when the pilot light goes out, it's literally a few seconds between flicking on and off. I was told by the boiler engineer that this wasn't an issue with the boiler but an issue with the internal thermastat in the shower itself, but while running any other taps in the house, bath, sink etc this is still happening. I'm thinking this isn't the shower thermastat at all but more an issue with the boiler itself. While hot water is running shouldn't the pilot light continue to be on whilst the hot water is running? Hope someone can advise. TIA

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5 Answers

UK Gas Engineers

Rating: 5 out of 5
Nottingham
If this is happening at all hot taps it is more likely an issue with the plate to plate heat exchanger ( blockage) causing the over heat safety device to activate switching burner off and when it cools on again
Answered5 July 2022
4

FM Heating Essex

Rating: 4.9 out of 5
Chelmsford
Assuming that this is a combi boiler you are talking about, and you haven't mentioned if the heating side is OK or not. I would investigate the gas valve, gas inlet pressure, pump, and the plate heat exchanger.
Answered5 July 2022
2

Art to Plumber

Rating: 5 out of 5
Sutton In Ashfield
The boiler small heat exchanger need cleaning or the pump not circulating
Answered5 July 2022
1

Anonymous user

Most often cause is as noted above and likely the secondary heat exchanger. However if replacing I’d also have your engineer look at water quality and also possible magnetic protection on the boiler return.
Answered12 July 2022
0

AWPS MECHANICAL LTD

Rating: 5 out of 5
Dunstable
Plate Secondary Heat Exchanger is partially or Blocked so Circulation is not going round the Hot Water Circuit. Water is being Heated but as there is no Circulation, will rise to High Temp telling the Boiler to turn off and then back on again. Causing intermittent Boiler Fire. Remove Plate and dip in Hydrochloric Acid to clear Debris. Or replace. It just needs a Clean. Depending on Which Boiler, should be straight Forward.
Answered12 July 2022
0