1973 DuoTherm Furnace Model#75003 Help
Posted: Mon Feb 16, 2009 5:06 pm
Hello to all, am having a problem with furnace burning too hot even with inlet gas line pressure at 11.0 WC inches and with gas valve outlet pressure set to same for LP gas. The place I purchased a replacement valve from insists that it is the correct valve(RobertShaw 720-472 24 volt step-opening combination gas valve) to replace the original part#H-3226 The air intake is clear, registers are not blocked, as far as I can tell flue is clear and I vacuumed inside of burner box-this is all that I can access to clear soot out. The only way I can get it to burn what I think is properly is by turning the supply gas shut-off valve about halfway closed-this results in the WC inches manometer reading 3.5-yes I have turned over the gas converter on valve for LP conversion. Furnace info plate says 65,000 btu input-replacement gas valve control instructions say 15,000 min to 280,000 max. I assume this to mean anything which falls between this limits is ok. I'm wondering if this is a case of the model made for manufactured home being slightly different and a "universal" gas valve not being the right remedy. Also if it is possible for there to be soot where I can't get to it, can see heat coming out of top of flue on roof so I am assuming it is clear. Any help/suggestions would be greatly appreciated.
Thank you, Sean
Thank you, Sean