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Furnace pro's, have a question

1981K20

1981K20

Up North
Joined
May 19, 2020
Member Number
369
Messages
219
Loc
North of MT but south of AK
Trying to help our elderly neighbor, her husband is no longer around and money is tight.

Her furnace short cycles. There's no flame sensor as it pre-dates those so I'm at the point where I think it's her thermostat. I'll fix that, but upon inspection I found 2 cracks and some burnt tin foil insulation. Also found evidence of the insulation dust around the whole unit, I cleaned it up and more was present the following day.

There's an insulated panel above the burners and there are 2 cracks in the sheet metal surround that it screws into. This panel is the one with deteriorating tin foil insulation.

Can I weld these cracks or is it indicative of deeper issues?

I know she needs a new furnace, this one is an Inter-city unit from 1977. Unfortunately that's not an option right now and winter is coming.

Any thoughts or insight would be appreciated
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Check those flames for color and inspect the vent. I almost died from a fucked up vent on the furnace. The vent rusted out, and carbon monoxide filled the house. Carbon monoxide detectors saved us.

This isn’t an appliance that’s bad, but you just run it anyway,

I’d say it’s got a flame sensor or roll out. Sensor that’s not working and shutting it off when it doesn’t see proof of flame.

Is there a wiring diagram you can read on the cover?
 
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I’d bet it’s cycling on limit, take the cover off the fan/limit switch above burners and fire it off, you’ll likely see the switch rotate until it hits ~250° and the flame cuts out. Watch the flames pretty close when the blower comes on, that can tell you if there is a crack or hole, a crack can also open up as chamber gets to temp and start impacting flames. She should have atleast one CO detector in that house.
The cracks in your pictures aren’t too concerning to me, they are on the plate the chambers are bolted to not the chamber itself, a result of the heat from burners “fuming”, usually caused by a dirty pilot sooting up the chamber causing poor draft. That’s kind of a hot spot area anyway somewhat out of the direct blower airflow, when the blower turns on that crack is under positive pressure so CO isn’t much of a concern imo. It will make a mess but you can blow the chamber out with leaf blower, vacuum, compressed air etc and get a better draft and more complete combustion. Blow into the chambers from burner area as well as into the draft diverter. The insulation dust you are seeing is probably just white soot.
 
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She have a carbon monoxide detector at least?

Or planning for the long sleep with firing up that 50 year furnace?

Stories like these is why I buckled down a few tears ago on putting $$ away. I'll be damned to be an old grumpy fuck having to not freeze by jerry rigging an antique heater while eating clearance rack hot dogs and kraft dinner.

Least I'll be a warm old grumpy fuck.
 
FJC11 said:
I'd pay for a service tech to come in and give you an honest assessment on that furnace, better than not waking up one day.
Click to expand...
85% of the service techs that you call will condemn immediately.

Unfortunately, they want to sell the furnace and with the side benefit of “cover my ass “
 
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grumpy356 said:
85% of the service text that you call will condemn immediately.

Unfortunately, they want to sell the furnace and with the side benefit of “cover my ass “
Click to expand...
I’m kinda getting that way but on the safety side not selling. Too many people have old ass furnaces with very little safeties if any beside thermocouple and main limit. Couple that with no maintenance or routine checks and it’s just not worth it to me.
 
grumpy356 said:
85% of the service text that you call will condemn immediately.

Unfortunately, they want to sell the furnace and with the side benefit of “cover my ass “
Click to expand...
There's got to be an old school fixer somewhere.

I know where I grew up in Maine if techs didn't nurse it along and just want to put new they'd go out of business.
My sister's husband does that work, mostly oil burners and he's worked on stuff that was WW2 vintage.
 
1981K20 said:
no flame sensor as it pre-dates those so I'm at the point where I think it's her thermostat
Click to expand...
Keep in mind the stat is just a switch that says "make heat" or "No heat". Pull the stat, short the wires together, and see what the furnace does. Eliminate variables.

Also, all the safety cutouts are usually on one loop. Flame sensor, rollout, etc. If they're sensing what they should, that circuit is continuous and the furnace gets to working. Or if someone jumpers past them for diagnostic purposss.
 
Find oldest guy in town and pay for an hour diagnosis.

Personally I wouldn’t mess with it due not being able to afford to build her another house, or if the heat exchanger gives out and fucks her up.

I used to put my ass on the line rebuilding propane tanks and little side jobs but I don’t trust people any more, plus I don’t have to work on weekends any more either.
 
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So I tripped the old mercury based thermostat and it runs a full cycle, pretty sure a new thermostat would help her lots so I'll buy and install it but only after the gas company does a (free) safety check. I helped her set that up for Tuesday.

I checked the burners, actually look great and seem to be providing uniform flame with no visible issues. Adjusted the pilot light down a bit and I bought her a new carbon monoxide detector. That's the extent of my help for this one, got enough of my own junk to fix.

Thanks for the replies!!
 
Cracked firebox means it's seen too many heat cycles...that's gonna put carbon monoxide into the air. I would not be a part of making that thing work again.

Not what you want to hear, but it's the truth.
 
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