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Weak flame, melted wires

Posted: Sat Jan 01, 2011 5:01 pm
by wyoguy
You fellas have a great web site and are preforming a wonderful service. Thanks in advance.

Year 2000
Nordyne M1MB 090A BW propane conversion
Ser # M1M 000402954

Two weeks ago, this heater quit with four red flashes on the Control Module status display(lockout due to failed ignition). I had an HVAC tech check it out. He replaced the original coil igniter with a solid igniter and that seemed to work for a short time. We woke up with the heater not working. I called the HVAC tech the next morning, leaving messages. Have never heard back from him??? Hmmm.

The heater had tripped the circuit breaker. I removed the front cover thinking the filter was a problem. It ran ok for a few cycles, but the yellow light was flashing on/off with the "weak flame" signal. It would run for an extended period with little heat coming from the registers, although the flame was definitely on...weakly. It eventually shut down with the four flashing red light signal again. In the last few days I have recycled it a few times with the same result......yellow flashing light--shut down--four red flashing light.

I removed the burner assembly thinking your suggestions on cob webs/obstructions in the burner could be a problem. Everything is clear. However, I found that the new ignitor has melted wires (both) from the ceramic attachment points to about three inches away . They were not touching, however, one of the wires is only held by two strands 2.5 inches from the ceramic piece.

I am assuming this is not normal. I can't tell for sure if the wires ever shorted. The ignitor is still working, but the other problem remains. Any suggestions would be appreciated.

In case your are wondering, we have a corn stove and are using the furnace as a backup. So, we are not freezing in this below zero weather. The heater runs on occassion and has worked properly this winter up to the start of these problems. I am going to attach a photo of the igniter.

Thanks

Re: Weak flame, melted wires

Posted: Sun Jan 02, 2011 2:13 am
by Robert
Hi,

Did you inspect the burner orifice/spud (spider-web-bugs) behind the gas valve before the burner ?

Also check the voltage to ignitor and replace ignitor with OEM.


Thanks,
Robert

Re: Weak flame, melted wires

Posted: Sun Jan 02, 2011 2:11 pm
by wyoguy
Hi Robert,

I did a visual check of the orifice. Looks clean. Should I remove or blow it out?

Voltage measures 120V, after the 45 sec delay.

I see that the web site has three coil type ignitors, but I don't know which one I need. The Tech took my old one with him. Could you help out with the correct one to order?

Thanks,

Dennis

Re: Weak flame, melted wires

Posted: Sun Jan 02, 2011 9:52 pm
by wyoguy
I think I have found the part number I need.....903110A.

Thanks,

Dennis

Re: Weak flame, melted wires

Posted: Sun Jan 02, 2011 11:12 pm
by Robert
Hi Dennis,

Yes, remove orifice/spud and thoroughly clean out.

How long does it maintain the 120VAC to ignitor ? Should be around 30-40 secs. total. Usually 30/35 secs. and then around 6 more once gas valve opens.


Ignitor # 903110A can be seen and ordered from here by paging down :

http://www.aberdeenhomerepair.com/store ... esults.php



Thanks,
Robert

Re: Weak flame, melted wires

Posted: Mon Jan 03, 2011 10:10 am
by wyoguy
Hi Robert,

Yesterday, I put shrink tube on the exposed wires and put the furnace back together. Ran it once and it shut itself off after about 10 minutes. This morning I tried it again, and it has ran for about three cycles (normal thermostat controlled) without incident.....except for the blinking yellow light and lukewarm heat.

I have to leave soon, so, I will take it apart and remove/clean the spud this afternoon.

Thanks,

Dennis

Re: Weak flame, melted wires

Posted: Mon Jan 03, 2011 2:12 pm
by Robert
Hi Dennis,

I would get that ignitor replaced as soon as possible. The way those wires looked, wouldn't put much if any trust in the shrink tube fix. Just not worth the risk of a fire.


IF the burner and the burner orifice/spud are ok, then may need an hvac tech to check gas pressures at inlet and manifold side of gas valve.



Thanks,
Robert

Re: Weak flame, melted wires

Posted: Sat Jan 08, 2011 1:23 am
by wyoguy
Hi Robert,

Sorry this took so long to get back. I took it apart again and the shrink wrap insulation was charred. Spud was clear. Had a different HVAC tech come to check it out yesterday. He installed the correct igniter, with the flame sensor in it and all is working correctly.

Thanks for your help with this!

Dennis

Re: Weak flame, melted wires

Posted: Sat Jan 08, 2011 2:05 pm
by Robert
Hi Dennis,

You're very welcome, happy to help.




Thanks,
Robert