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Ghost in the Thermostat
I was called out to a home in the city for a No
Heat Call. Really they said it was that the Heat would go on then off, over and
over. They have had out a number of contractors already but nobody could figure
it out. So I was the EXPERT who would solve this problem.
When I arrived I went to the thermostat and
check it all seemed to be in good order, so onto the basement. Sure enough, the
furnace was short cycling (going on and off.) I decided to cut the wire to the
thermostat and mount one downstairs to make sure the problem was not in the
furnace itself. After about 15 minutes I had gone thru all possible problems it
could be and labeled the furnace as OK. I hooked up the thermostat wire again
and there it goes again OFF, ON, OFF, ON. So I thought it must be the thermostat
or the wire. I go upstairs and take off the cover of the thermostat. To my
surprise I find but a bug sitting on the mercury bulb walking from one side to
the other causing a little flash of light and cycling the furnace ON and OFF. I
guess when the bug needed to be entertained it went to the thermostat for the
light show. |