Furnace Door Switch - Safety Feature or Functional Necessity?


Old 01-18-13, 01:04 AM
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Furnace Door Switch - Safety Feature or Functional Necessity?

there is a switch on my furnace that shuts it down whenever I remove the front panel. I assume this is a safety feature. Does it serve any other function other than interrupting the AC power line? Maybe filtering? Or a fuse function?

I have a degree in telecom electronics and have worked on lots of radio equipment but no furnace experience. I understand the safety reasons for switches like these. but in the event the switch fails is there any harm in removing it and simply connecting both leads together until I get a new switch?
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Old 01-18-13, 01:17 PM
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The purpose of the door switch is to prevent the operation of the furnace if the fan compartment door isn't in place.

If the furnace is operated without the fan compartment door in place, a powerful negative pressure developed by the fan will cause combustion gasses and perhaps even flames from coming out into the burner compartment instead of going up the heat exchanger and out the vent pipe.

Interfering with combustion can also cause large amounts of carbon monoxide to be produced, and the fan will promoptly circulate this poisonous gas into the living spaces of the dwelling.

And it's not especially unusual to find people trying to operate the furnace without the door, or with the door installed improperly.

So the key thing is that the door must be installed correctly. If your switch has failed, I'd make a point of replacing it rather than just removing it and bypassing the switch electrically. You might be saving some future user a bad experience.
Old 01-18-13, 03:49 PM
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thanks so much for your reply! I assumed it had something to do with keeping consumers from getting electrocuted, burned or injured by a fan component. Never realized the door is a critical part of the air flow. This is very good to know!
Old 01-18-13, 06:26 PM
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If you buy a new door switch before you need one, you will never need it.

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