Pilot Light Blowout

[MasterPlumbersKeymaster]

Have a wall mounted gas heater in a garage that has a pilot light that blows out only when the temperature approaches or reaches the set temperature. Whats going on? Don F

[GuestParticipant]

Pilot gas is usually drawn from the unregulated supply pipe before the gas control regulator. This means that changes in street pressure and flow in the supply pipe can change the size and quality of the pilot flame. If the gas pressure has changed without the pilot flame being readjusted to produce a strong flame, a lazy flame due to lowered pressure can be drawn away as the gas valve shuts down flow to the burner. For a short time after the main flame goes off, the exchangers are hot and continue to draw air throught the appliance; however there is no longer a flame to fill the exchanger so more air is drawn through to move the flame away from the thermocouple and shut down the pilot.

[GuestParticipant]

Thxs Harold. This appears to be exactly the case. The pilot tube does not appear to have any adjustment, or at least I can’t spot it. I’m going to fabricate a small sheet metal shild to surround the pilot from excessive air flow. If you have any additional thoughts I would appreciate them. Thxs again. DonF

[DPParticipant]

Let caution prevail.

I am a registered Gas fitter (in Britain) I am not permitted to alter or change any gas equipment. To instal sheild and suchlike result in explosive ignition as the pilot flame is positioned to ignite burner gas. Put a shield in between, you could end up with a pocket of gas that will eventually ignite but it may not be gentle.
Talk to Herold again as he will be able to provide you with a more precise answer

[GuestParticipant]

Precisely DP. However, I could not, in good conscience, give more advice about how to adjust a gas appliance to an inexperienced person. The customer should know the reason that the manufacturer’s instructions require ‘a qualified repairman.’ The danger to the family is not worth the risk to save money. GB’s laws are more explicit than the US.

[Author]

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