Gas Heater Kicks On, w/Main Disconnect Shut Off?


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Old 03-04-06, 11:36 AM
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Gas Heater Kicks On, w/Main Disconnect Shut Off?

Maybe this is gonna be too obvious, but I can't figure it out.
Doesn't the thermostat for my gas heater need electricity
to work? I shut off the main disconnect outside, and when
I turned my thermostat up, the heater kicked on.
How is that so?
Wouldn't there have to be an alternate power
source for it somewhere?
If it's low voltage, I guess it could run off batteries, but
I don't see any batteries anywhere.
I'm sure there must be an obvious, simple explanation.
I must be overlooking something that's staring me in the face, huh?!?
 
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Old 03-04-06, 11:41 AM
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Please descrive the furnace.


Wall heaters with no fan operate just like your water heater. A device called a thermocouple, also similar devices called pilot generator, when heated by the flame of the pilot light, actually generate a very small electrical signal in the range of 0.07 to .7 volts. The gas valve is designed to use this tiny electric current to open the flapper.
 
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Old 03-04-06, 11:49 AM
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Oh!! So it generates its own power, from the pilot
flame. Well, ya learn something new every day!!
I thought I was going crazy, or imagining things.

The heater is about 5 1/2 feet high, 18 inches wide, and it's mounted in the wall.
It is a "Commonwealth" heater, very old, I'm sure.

So if the power goes out in my neighborhood, I will still have heat.
That's nice to know!! Thanks!
 
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Old 03-04-06, 03:01 PM
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594rough hit it right on the head. When I lived in CA, My house had two wall heaters that operated on the voltage developed by the pilot light.
 
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Old 03-04-06, 07:21 PM
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With any gas applience, and especially an old one, it is ESSENTIAL that you install a carbon monoxide alarm. Newer wall furnaces like Willimams have safety circuits to shut down in event of blocked flue. Yours probably has no such safeties, and one of the things that can fail eventually on an old furnace is the heat exchanger. A crack will allow CO to enter the room.
 
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Old 03-04-06, 08:13 PM
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tough, thanks for ALL the info. I'm picking up an alarm tomorrow.
I don't wanna croak in my sleep, at least not 'till I'm 90 or so.
 
 

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