GM Delco-Heat


Old 11-12-08, 12:15 PM
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GM Delco-Heat

My home heating plant is a forced-air, oil-burning GM Delco-Heat Model OP0100 H rated at 100,800 BTUs. I suspect the unit is about 50 years old, but we have only lived here 32 years. (GM has not made home heating plants for at least 40 years.) The Limit & Fan switch has a problem. The fan does not shut off when the bonnet is cool unless you wrap the unit gently with the handle of a screw driver. Inside the unit, there is an S-shaped spring built into the fan switch's blade to provide hysteresis (on-off differential). It seems to be sticking. Lubrication did not help. Any service suggestions? Any suggestions for parts sources for this dinosaur?

(Please do not suggest replacing the heater. In today's market the house is not worth it. Besides, it was installed using the basement stairs as the cold air return. A new unit would require installing return ducts to meet code.)
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Old 11-12-08, 04:26 PM
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Were you actually able to take the fan switch apart when you tried to lube it, and perhaps inspect and analyze to see if there was anything you could do?
Old 11-13-08, 06:42 AM
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I don't remember what style fan/limit they used on the Delcos but I suspect a Honeywell L4064 series would work.

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