Nordyne/Intertherm weak flame - furnace off?

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Posts: 17
Joined: Sat Jul 07, 2012 8:19 pm

Sat Jul 12, 2014 6:25 pm

I replaced my furnace back in 2009 with a Nordyne/Intertherm M1M B077A AW. It's A/C ready but I haven't gotten around to getting central air installed yet (although I wish I did - it's 35 C here today!)

I have this peculiar problem with the furnace. It's happened twice (once last year, and once just last week.)

In the middle of summer, the furnace fan kicks on. The thermostat is OFF. Like, no calls for heating or cooling. But the furnace started and the code was blinking weak flame. I was a little confused, the combustion chamber was not warm and when I looked through the investigation flap the burner wasn't lit at all. I reset the furnace by shutting it off (using the switch behind the furnace door) for a bit (maybe 10 minutes?) and turning it back on again.

I was outside no more than 10 minutes and I could hear the furnace running again. Again, no flame at all. I switched the furnace off and it's been off since then.

That day there was smoke in the air, someone in the neighbourhood must have been burning something or other and I did have all the windows open to my place.

When I turned the furnace on last fall (it did do this last summer as well) it worked normally.

Could outside smoke have triggered the furnace? Or perhaps is something worn out? I find that hard to believe, the furnace isn't quite 5 years old yet (will be in October.)

Posts: 385
Joined: Wed Apr 07, 2010 10:07 am

Mon Jul 14, 2014 6:26 am

How warm/hot was it in the house when this happened? I could be wrong but there may be a setting in the board that will turn the blower on if a limit switch cuts off. It would be a safety feature to cool the unit down whether it is calling for heat or not.

This blower coming on thing was quite common on the older units that had temperature activated blower switches. The M1 furnaces have blowers controlled by the boards.

Posts: 17
Joined: Sat Jul 07, 2012 8:19 pm

Mon Jul 14, 2014 2:44 pm

I don't think it was terribly hot, maybe 25-26 C (maybe 76 - 80 F)? I live in a more humid environment though, relative humidity is typically 50% here during the day. I just looked now and the humidity is 61%.

I remember having one of the old Intertherm furnaces that had a temp switch and when it got to 30 C in the house it would turn on the blower blowing hot air everywhere. I know for sure my place wasn't that warm. It has only done it twice so far, and I have a curtain in the hallway to help my window A/C, so on really hot days it'll be comfortable in the living room but 30 C in the hallway and it wouldn't come on then.

I figured because these are electronically controlled it shouldn't be kicking the fan on, but maybe I was wrong.