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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.


    EBEBRATT-Ed Member Posts: 13,750
    12.5 for propane is a little high. Most say 9-11" wc try lowering it a little. Make sure all burners are in the correct alignment
  • Tim McElwain
    Tim McElwain Member Posts: 4,593
    Did you check that gas pressure after the gas valve? If so try reducing the gas pressure to 11" W.C. check the orifice size and make sure it is as close to input as you can get it. If you do not have LP charts post the orifice size and gas pressure here and I will chart it out for you. Also reduce primary air slightly that will sometimes correct the problem you are having.