Pilot light lit, but burner will not?

in a hot water heat system , once thermostat is set high the circulators are on i could hear the water going , pilot is on but burner won't start?

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  • 4 years ago
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    See if there is a flue damper in the flue pipe (to prevent loosing heat up chimney when burner is off). If that either does not open or the open switch fails when thermostat calls for heat, the gas burner will not kick on.

    I have a steam boiler and previous owner had the pressure switch cranked way up and I found out why when I set the pressure down where it should be (as low as it goes). The flue damper would open when cold, but when the pressure switch cycled the boiler and it closed, it would not reopen when hot until is cooled down. Replacement worked for a number of years and then it malfunctioned and I had to lock it open until I can replace it.

  • 4 years ago

    There could be a number of reasons. It could be as simple as your thermostat or thermocouple, but more than likely it's more complicated like your ignition module, blocked flue, limit switch, aquastat or gas control valve. Gas boilers are extremely DANGEROUS to work on if you don't know what you're doing. Please call you local furnace repairmen before you blow up your house!

  • 4 years ago

    in the uk you are not allowed to touch it ...only a gas safe engineer ...but it sounds like thermocoupler ...easy and not too expensive to replace

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