Im Back-yellow flame problem guy

[bluestom50]

Unit starts ,goes through purge cycle, burner lights after flaring up 4 or 5 times-- works really well with 4 burners or less lit-- will bring temp up like it should-- shut off and turn on when temp falls as it should-- If i set temp higher and all burner lights come on I get a big yellow flickering flame and after a minute or so the unit shuts down and lights flash. Also, just before room circulating fan come on it makes a wavering sort of high pitched howl which sometimes last 20 seconds and sometimes a minute before going away. It doesnt seem to be either fans making the noise. Once again I am stumped and really would appreciate any help you can give.Thanks,Tom

[dfitz3390]

If i remember correctly there are only two rotating parts in the unit, the combustion blower motor and the air circulation fan motor. have you rebuilt or oiled the combustion fan motor ? the air circulation motor shouldnt cause any change in the burner unless it stops working and shuts off on hi temp let us know Dan

[dfitz3390]

M422, 1996 From previous post by Hawkins A Monitor 422 built in 1996 was one built in only the second year of that models run. You may have one of the early ones that had bushings instead on bearings in the combustion motor. If so, you can oil them if they are not worn too bad. You can tell right away if you have one by looking at the bearing cap on the motor. If it has a black rubber stopper in the cap it has bushings. This may save you some trouble as they can be oiled

[HayZee518]

circulator fan

the motor if it uses sleeve bearings are made of a substance called OIL-LITE. This is a sintered bronze bearing which is porous enough to retain a light oil throughout. adding oil to the ports will give you long life. look for the oil caps. like dfitz said.

[dfitz3390]

in the last unit i had with that specific motor , under the bushing caps were plastic thrust washer that degrade without oil and allow excessive shaft play and the combustion fan hits the housing. luckily i had an old one and used the washers Hayzee, any idea why the save edit button isnt working ?

[FordMan59]

Although I don't know as much about these heaters as most of the other regulars on this forum I'd begin by taking a look at the fan bearings/bushings. My son and I both have 422's, both have the rubber plugs that can be removed to oil the bushings. The yellow flame would make me think maybe it's something to do with the combustion motor. One time when my 422 began shutting down during the heating cycle I loosened the flame rod and moved it around a little bit and tightened it back down and it resolved the problem. I've always suspected there was carbon between the flame rod and burn ring causing the heater to go into lockout mode.

[HayZee518]

flame rod

you can always test the flamerod or circuitry by making up a test setup. Use a 1N4004 diode in series with a 100K ohm resistor. When the unit calls for heat jumper out the flamerod by connecting one lead to the rod lead and the other to ground. if it shuts down reverse the wires.