Munchkin 80M Ignition Failure- Help

Mars_3

Could be bad flame sensor wire or spark wire, could be bad board, might be bad flame sensor but thats low on the list. Good luck

Larry_55

Old Munchkin Ignition Failure ....

I can't figure out what might be wrong.
This is one of the original munchkins (11/01). Controller board led gives 4 flashes. Fault Description is "Ignition Failure (No Flame)".

The boiler igniter looked fine - I replaced it anyway and I get sparking when it's trying to light.
I get gas to the shutoff valve. The blower is working. The venturi is not clogged or falling apart (this happened a couple years ago).

The boiler has always run very clean. Very light white buildup on the heat exchanger in a year (easily removed with a scotchbrite). The inside around the gas valve is always clean and bright.

Any suggestions on what to look for would be much appreciated.

Thanks,
Larry

kpc_75

bad ground...

spark going to ground, is the dain draining the condensate properly? of the refractory is wet it will pull the sparl away from the flame sensor.

Larry_55

Thanks for taking the

time to think about this and reply.

I see a spark when it's trying to ignite. Would there still be a spark if the wire is bad? Any other way to tell if it's bad except by replacing it - check the resistance?
I'm not sure how to check the flame sensor wire either -- maybe just look at resistance with that too?
I'm guessing you check the board just by replacing it -- is that right?

The condensate seems to be draining and looks the same as it has before. It did clog up before, but it doesn't seem to be doing that now. The refractory didn't feel wet when I had it apart -- it seemed bone dry.

Is there a way to check to see if a signal is going to the gas valve? There are two wires going to a four hole plug and I can't see which have the wires? I'm guess there should be 24V gong there, but I don't want to mess anything up.

Thanks for your help.

Larry