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Im Stuck!

Josh Williams
Josh Williams Member Posts: 2
Hello, I am working on an oil fired hot air furnace.  The oil tank is in the basement and the furnace is in the attic.  It is a 2 pipe system and both the supply and the return are 1/2 inch lines.  There is a check valve in the supply line.  The system will fire up and run for approximately 2 seconds then the flame will stop and the system is still running for 2 seconds then the flame will ignite again for 2 seconds and the vicious cycle repeats until the primary control trips.  The system was not being used for the past year and I changed the oil pump and bled out the line and I put the bypass plug in the pump.  I am stuck and dont know what else to check, any ideas?


  • toilburn
    toilburn Member Posts: 44
    Check Valve

    You don't need the check valve.
  • OilsBetter
    OilsBetter Member Posts: 14
    edited March 2010
    I agree

    Lose the check valve and double check all your fittings to make sure no air is entering the line. Prime it and check to be sure all the air is gone before trying to run the unit.

    Did you change the oil filter and strainer? (assuming it has one)
  • billtwocase
    billtwocase Member Posts: 2,385
    check valve

    I don't think that's your problem. why 1/2" lines? Firing rate? By-pass plug in? Vacuum test? What filter do you have, and where is it mounted? Any couplings along the way? So many other possibilities when not gravity fed
  • billtwocase
    billtwocase Member Posts: 2,385

    I see you do have the bypass plug in. Did you use a 2 stage pump? Coupling good? Too much air for combustion?
  • Jim Hankinson
    Jim Hankinson Member Posts: 99
    Stuttering flame

    Run the nozzle line into a container and watch the oil flow. If it runs in spurts it's a fuel supply issue. Any air bubbles, suction leak is quite possible. Was the original pump a 2-stage? How about a Tiger Loop and 1-pipe?

    I don't know what state you're in but in NJ 1/2" od is code for oil lines.
  • Tony Massi
    Tony Massi Member Posts: 86
    Stuck in the Attic

    Hello, It sounds like it could be air in the line. You could get an oil watcher and see if there is air in the line also it will tell you the vacuum. Also the oil line could plugged at the tank. If the vacuum is more than an "A" pump can handle  you might want to try a " B " pump, it may help.
  • Charlie Masone
    Charlie Masone Member Posts: 66
    Just say no to two pipe

    did you put a vacuum gage on?  Loose the return and use a TigerLoop
  • Techman
    Techman Member Posts: 2,144

    I agree with the others ,put on a vacuum gauge and see. There is 1" of vac for each foot of rise , 1" for each of the check valve, firematic, and oil filter.Your pushing the limits of a "B" pump let alone an "A" pump . What burner gun do you have?
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    what Charlie said

    You have to figure at 1" per per vertical lift I would expect your vacuum to be in the 12-15" Hg range, if not more. I've seen 20" + in an application like that. You would be almost over TWO stage pump limits, if not, the oil is getting stretched to foam.

    Like Charlie said, Tiger Loop it, drop the return line and any check valves, and make sure all connnections are flare, and perfect flares at that.
This discussion has been closed.