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Old Warm Morning = cold heart
So my very old Warm Morning gas heater has been having intermittent pre ignition / flashback problems. I have cleaned the cast iron burner several times. Checked the orifice, it’s clean. Adjusted primary air. I checked the manifold pressure today while running several cycles, reads 12.5” W.C. It is factory built for LP. Sometimes the heater will pre ignite, sometimes it will run fine, other times it will flashback to the orifice. Very inconsistent, it has an old Honeywell V8254A control valve which appears original. This valve has no test ports. At first I suspected low gas pressure, but the test confirmed it is in range for most LP equipment. The manufacturer plate has no W.C. Rating.