burner wont ignite

Old 10-04-04, 02:36 AM
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burner wont ignite

my parents have an older rheem, central heat and air, standing pilot natural gas, about 14 years old, they are however on a very fixed income and replacing the unit will have to be a VERY last resort.... they have a CO detector and it has never showed sign of CO... last week the furnace was turned on for a short period of time in the early morning.... worked fine that day.... since that day they have tried to turn it on again in the early mornings, and the burners will not ignite... from the tstat you can turn on the a/c unit and it works fine, you can turn the tstat to "on" position for fan and fan runs, i believe they told me the fan even comes on when the tstat is turned to the heat position ( not positive about that one). i asked them if the pilot light is staying lit and has good flame, and it does. first i was thinking the thermocoupler, but if that was the problem wouldnt they have problems with the pilot light as well? i am going down tomorrow to check a few things like 24volts at the gasvalve and do the jumper wire on the R&W wires at the tstat and check the heat sensor for cleanliness.... was hoping someone may have some other suggestions for me to check
Old 10-04-04, 01:50 PM
Ed Imeduc's Avatar
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,386
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Sounds like you have it all there. Make sure the pilot light is clean. Yes can be that when the tstat calls for heat on some units it will turn the fan on after a little bit.Check out the schematic there on the blower door.

Old 10-04-04, 02:42 PM
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thanks Ed i am here now working on the furnace..... what i have found is that when you remove the bottom service panel.... the safety switch that is supposed to shut the power off to the fan and the gas valve.. it actually is working opposite what it should meaning that when the door is removed, everything works properly.... i tried switching the two wires coming out of the switch thinking it was wired backward somehow, and no matter how it is wired it still works reverse of what it should..... how unsafe is it to just wire around this switch?

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