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Intermittent spark ignition issues

joseph annon
joseph annon Member Posts: 51
I have a boiler that is about 1 year in service a Lochinvar CBN500. A copper fin tube 500,000 btus.

Problem is that the boiler has been not firing.

My question is about the ignition module. It seems to me that the pilot staying on sets the module in flame proved step but without the spark step it does not go the full burner or even pilot open step. Does this make sense?

Back story on what I have found.
If the power is disconnected for a while then reconnected sometimes the boiler will fire.
Have gone through the local rep and tech support at Lochinvar and manual and conclusion is that the ignition module is bad. Which means the new one recently installed has failed and new one out of box has failed. Unlikely I think.
What I have found that is unusual is that when checking on the pilot assembly it was hot. Can't really see the pilot so I was not sure why the assembly was hot. Boiler had not fired for 12 + hours. So should be cold. Pulled the assembly out and removed the igniter from the assembly and tried powering up and the it sparked. (burner manifold was manually shut off.) Reassembled and it sparked again and lit the pilot. Then cut the power and the pilot faded to about half of operating level and stayed there. Would not go out. Probably a problem with the gas valve not completely closing on pilot. Gas valve replacement is on order. Reinstalled pilot assembly no spark. Pulled out pilot assembly again and grounded it and it sparked. Decided that I needed a better ground for pilot assembly. Tried that and there was spark ignition. Boiler operated through multiple on off cycles.

Thank You


    HVACNUT Member Posts: 4,858
    Make sure the ground is good all the way back to earth.
  • heathead
    heathead Member Posts: 217
    If the pilot stay lit the gas valve is bad. The ignition module is sensing the pilot is never going off. When you shut of power the pilot signal is lost. Then it lights and works, but if after the cycle is done and the pilot stays lit the control module thinks something is wrong because the pilot flame signal stay on all the time. Just a thought.
    joseph annon
  • joseph annon
    joseph annon Member Posts: 51
    heathead My thoughts also. Gas valve on order.
  • joseph annon
    joseph annon Member Posts: 51
    I replaced the gas valve and lock outs have ceased. I did talk to a rep for a different line of boilers and mentioned the issue and he did say the ignition module has a feature in it that if it "sees" flame when it powers up it won't run the igniter.
    EBEBRATT-Ed Member Posts: 13,101
    @joseph annon

    Good fix glad you found the problem. Did you find any dirt or pipe chips in the old gas valve?