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Suburban heater kicked the bucket


Devilishjim

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So my Suburban heater squeeked 6 months or more ago and then started working good again. I kind of figured a fan bearing going bad. But a couple days ago it didnt squeek it Squallered and came to a screeching halt !

 

I got it disassembled today and found the combustion wheel melted to the housing ! Freed the wheel and it spins great. I havent tried the motor yet but think it will run just fine.

 

BUT this was the most nasty project ive had. They built cabinets around this heater and a sink right above it and brought the water lines in...You guessed it right in the way ! This simple job took me all day.

Now my question is why did this happen Heat tweek the plastic wheel so that it would rub ? It doesnt look like it moved on shaft.

I hate to buy a new motor but I dont want this happening again either.

So I'm thinking a new motor and combustion wheel any ideas or pearls of wisdom ?

And why is the room air fan metal and the combustion one plastic ?

Motor has no end play, spins nice and smooth, will test run it in vise tomorrow

Thanks for any and all input good or bad <_<

35000 btu no wonder that sucker guzzles propane ! Maybe I should just buy DW a pair of long johns :huh:

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it sounds almost like someone hooked up the motor backwards and it was pulling hot exhaust gas out the intake. I am surprised it would even run. You don't happen to have a mesh screen over the outside vents, do you. that might have made some hot gasses come in through the intake but I doubt it would have been that much.

 

Is it possible that the motor overheated so much that the shaft heated up enough to melt the fan blades attachment? Both of mine did the squeeling thing for a long time. Sometimes stopping for awhile. I eventually replace both of them and no problems since. But I will say that their demise was hastened by mud dauber and paper wasp nests built inside the blower and heat exchanger.

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I believe the plastic Fan supplies combustion air to the burner, I have never heard of any modern furnace using a fan to remove exhaust from the burner. Plastic would make sense as when you run the furnace the outside air being supplied to the burner would be cold and cause no problem. Metal would be required for the indoor side as the temperature of the supply air will often be over 130 degrees. I can not stand on my registers when the furnace is running for more than a few seconds with out the comfort factor on my feet being exceeded. I would chalk up the damaged wheel to a defective part. if a metal wheel of the same geometry and size is available, I MIGHT change it though I doubt it. The blower is designed to supply the correct amount of air to mix with the gas for the most efficient combustion for the furnace and I would be reluctant to change it for fear of running to rich or to lean and further damaging the furnace. 35000 BTU is why I use two electric cube heaters for most of my heating in the spring and fall.

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I believe the plastic Fan supplies combustion air to the burner, I have never heard of any modern furnace using a fan to remove exhaust from the burner.

While I have never tested the motor on an RV furnace, some DC motors will run in reverse if the polarity is connected backward. Even then I doubt this was the case since that would probably melt the plastic wheel in minutes, rather than to work at all. Our present RV has a Suburban furnace and this leaves me wondering if we have a plastic combustion air wheel? Our just past RV had 2 Atwood furnaces and the one prior to that was a Suburban but I had it out to work on it and know that both wheels in it were of metal. But it was also vintage 1987 so that means nothing on a newer furnace....

 

Like most Suburban furnaces, our current one is difficult to see and probably would have to come out to see much.... ;)

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I have seen a few plastic combustion blower wheels slide on the shaft and rub. Adjust them on the shaft for centering. Never had a call back, but.

Just curious if when the bushings get warm they may have made the shaft move. Never seen a wheel stick but things happen. I have seen that they have rubbed for a while.

 

 

Vern

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The space where the wheel sits has plenty of free space for centering the fan so wonder if the fan has to be a certain distance from the motor side of the housing ? The motor shows a manufacture date of 04 so it's the original and plastic shows no sign of heat except for where it rubbed on housing

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There is probably a spec for the free-play at either end of the motor shaft. Is it possible that the cage shifted toward the side it was rubbing against, and if so can you somehow lock it down to prevent movement in the future?

We only use this heater to take the worst cold out and then Olympian and electric take over.It was freezing hard outside so it was sucking very cold air and then got warmed up fast, Maybe the sudden change in temp flexed the fan ? The fan was fastened down tight on the shaft but there is lots of room to slide that fan over so it wouldnt rub against the housing which is plastic also. It's a squirrel cage type of fan so I dont know if it has to be set close to the back or motor side or not..There is plenty of room to move it over so it is guaranteed clearance.

 

I can see where the Dauber screens might be a good idea to keep mischief minded people from shoving something in the pipe which could end up nasty

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I always center or a little away from the motor to keep airflow in the direction it is suppose to travel.

I agree. That gives the most room for error. And try to make sure that the cage can't move on the shaft at all. Some shaft movement is normal.

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