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Heating, Air Conditioning, Fridge, HVAC/Natural Gas Wall Furnace Operation


My mom has an old Natural Gas Williams Wall Furnace.  The pilot light works fine but the burners will come on only when I jumper the red and white wires in the thermostat.  I tried replacing the thermostat but it seems as though the pilot generator may not be producing enough milliamps to activate the call for heat via the thermostat.  The thermostat is the old simple mechanical contacts type and the thermostat is located clear across a 20 foot room.  Is this problem something you have encountered before?  As well, any other troubleshooting advice would be appreciated.  Thanks, Dan

Using a meter that will allow one to do so, the millivolt signal needs to be checked.  It is also important that a thermostat be rated to work with with a millivolt system.  Not all t-stats are rated to do so.  I would think that if there was an issue, then it would not work at all.  I would lean more towards a t-stat issue then anything else at this point.


Heating, Air Conditioning, Fridge, HVAC

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Craig HVAC Expert


I have been in the HVAC field for the past 18 years. I can help with most HVAC questions. I work on commerical buildings for the most part, and have yet to find anything I could not troubleshoot and repair, when repairable. I work on small 1 ton units to a 2500 ton chiller. Troubleshoot air flow, elect, and control problems. I attend regular classes to keep up with the latest and greatest.


I work on commerical sites, hospitals, gov't buildings. I can troubleshoot just about anything in the HVAC business.

5 years trade school, VFD training classes, Liebert factory training, some York and Trane factory training.

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