Furnace Blower Vanes Broken

rxbristol · Nov 20, 2017

I pulled the Suburban SF-42Q furnace today because the motor would not start and found a brittle, broken, and melted seal of some sort that was internal to the furnace. What was it from? There are no burn marks in the RV or internal to the furnace. For the last couple of days I SOMETIMES could smell VERY faint burning odor, but I thought it was just normal furnace odor.

TravelTiger · Nov 20, 2017

Re: Melted Furnace Seal--Why?

rxbristol said:
I pulled the Suburban SF-42Q furnace today because the motor would not start and found a brittle, broken, and melted seal of some sort that was internal to the furnace. What was it from? There are no burn marks in the RV or internal to the furnace. For the last couple of days I SOMETIMES could smell VERY faint burning odor, but I thought it was just normal furnace odor.

View attachment 55589

View attachment 55590

Rex, we have the same furnace. I can't recall if you've seen that thread, but we're having issues with a bad smell inside the rig that's a burning smell.

Where is this seal? I don't recall seeing it when we took our panel off outside.

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rxbristol · Nov 20, 2017

Re: Melted Furnace Seal--Why?

TravelTiger said:
Rex, we have the same furnace. I can't recall if you've seen that thread, but we're having issues with a bad smell inside the rig that's a burning smell.

Where is this seal? I don't recall seeing it when we took our panel off outside.

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When I took the furnace out I heard some rattling inside...as I shook it all of the hard brittle pieces fell out. I did not see any of the pieces inside when I took the outside panel off, so the "seal" must be in the back of the furnace somewhere. I took off the back panel of the furnace before removing it from the RV which makes it easier to disconnect the back ducts...it might be the seal for the back panel is what I figure.

TravelTiger · Nov 20, 2017

Re: Melted Furnace Seal--Why?

rxbristol said:
When I took the furnace out I heard some rattling inside...as I shook it all of the hard brittle pieces fell out. I did not see any of the pieces inside when I took the outside panel off, so the "seal" must be in the back of the furnace somewhere. I took off the back panel of the furnace before removing it from the RV which makes it easier to disconnect the back ducts...it might be the seal for the back panel is what I figure.

Hmmmm. I removed the back panel when looking for our issue. There was not a seal on the back panel on ours.

Here you can see it set it on top of the furnace's metal housing.

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rxbristol · Nov 20, 2017

Re: Melted Furnace Seal--Why?

Now I wonder if the seal is between the burner tubes and the motor/fan?

rxbristol · Nov 20, 2017

Re: Melted Furnace Seal--Why?

I figured out what it is...half of the "Wheel, Room Air" turbine disintegrated. The pieces of the part prevented the motor from turning. Now I wonder what caused it to disintegrated.

TravelTiger · Nov 20, 2017

Re: Melted Furnace Seal--Why?

Rex, can you take a similar pic of the inside of your unit? I'm curious to see if they look the same.

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rxbristol · Nov 20, 2017

Re: Melted Furnace Seal--Why?

I took the housing off of the wheel turbine and found that pieces have been broken for sometime because dust was on the areas where the blades separated from turbine...that would explain the odor I was smelling as the blades went under the chamber and burner assembly. I'm not sure the motor is still good because it does not turn smoothly, but some motors don't.

- - - Updated - - -

Erika,

You should see the wheel turbine from the outside access area to see if it's in one piece and all the blades are intact. Since I had never seen one before, the wheel seemed fine and it wasn't until I got a closer look in better light that I could tell that half of it was missing. In the pictures I've attached, half of the wheel is missing.

danemayer · Nov 20, 2017

Re: Melted Furnace Seal--Why?

Erika,

You might take the cover off your blower and inspect the vanes. The sail switch needs 75% of full airflow in order to close and power the rest of the furnace, but as it blows less air, the combustion chamber would probably get hotter than normal.

rxbristol · Nov 20, 2017

Re: Melted Furnace Seal--Why?

danemayer said:
Erika,

You might take the cover off your blower and inspect the vanes. The sail switch needs 75% of full airflow in order to close and power the rest of the furnace, but as it blows less air, the combustion chamber would probably get hotter than normal.

Erika, the sail switch is in the housing around the turbine wheel...you'll see it if you take the housing off.

TravelTiger · Nov 20, 2017

Re: Melted Furnace Seal--Why?

rxbristol said:
Erika, the sail switch is in the housing around the turbine wheel...you'll see it if you take the housing off.

Wow, thanks for the pics and advice. Do you think the blower housing/cover can be removed without removing the furnace from the coach?

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danemayer · Nov 20, 2017

Re: Melted Furnace Seal--Why?

TravelTiger said:
Wow, thanks for the pics and advice. Do you think the blower housing/cover can be removed without removing the furnace from the coach?

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Yes. Watch out for the wires as you remove the cover.

rxbristol · Nov 20, 2017

Re: Melted Furnace Seal--Why?

TravelTiger said:
Wow, thanks for the pics and advice. Do you think the blower housing/cover can be removed without removing the furnace from the coach?

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Yes, there are a total of eight screws that you'll have to remove. Four that hold the housing, two hold a panel over the housing (that the circuit board is attached to) and two that hold another plate attached to the housing. Very easy.

TravelTiger · Nov 20, 2017

Re: Melted Furnace Seal--Why?

rxbristol said:
Yes, there are a total of eight screws that you'll have to remove. Four that hold the housing, two hold a panel over the housing (that the circuit board is attached to) and two that hold another plate attached to the housing. Very easy.

So is replacing the squirrel cage easy, or hard? I see there's one on Amazon for about $28.

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rxbristol · Nov 20, 2017

Re: Melted Furnace Seal--Why?

To replace the turbine, once the cover is off it will require a long 90 degree angled allen wrench, not sure what size, to remove the turbine from the motor shaft.

TravelTiger · Nov 20, 2017

Re: Melted Furnace Seal--Why?

Here's a similar thread:

2014 Rw 425 Furnace made single pop sound then I smelled propane exhaust.

https://r.tapatalk.com/shareLink?sh...wners.org/showthread.php?t=63341&share_type=t

I am hopeful this is our problem!

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rxbristol · Nov 21, 2017

Re: Melted Furnace Seal--Why?

TravelTiger said:
Here's a similar thread:

2014 Rw 425 Furnace made single pop sound then I smelled propane exhaust.

https://r.tapatalk.com/shareLink?sh...wners.org/showthread.php?t=63341&share_type=t

I am hopeful this is our problem!

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Great search find. I wonder if Twistedwest just changed the turbine and got it working again. I going to call Suburban in the morning and see if they have a metal substitute.

rxbristol · Nov 21, 2017

Re: Melted Furnace Seal--Why?

Well, I just changed out the whole furnace. The hardest job is disconnecting and reconnecting the ducts. The new one is quieter, more heat, and the circuit board location has changed slightly. I believe the quietness and increased heat is related to a whole turbine fan.

TravelTiger · Nov 21, 2017

Re: Melted Furnace Seal--Why?

rxbristol said:
Well, I just changed out the whole furnace. The hardest job is disconnecting and reconnecting the ducts. The new one is quieter, more heat, and the circuit board location has changed slightly. I believe the quietness and increased heat is related to a whole turbine fan.

Wow Rex, where did you get a new unit, and if you don't mind, share the cost?

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rxbristol · Nov 21, 2017

Re: Melted Furnace Seal--Why?

TravelTiger said:
Wow Rex, where did you get a new unit, and if you don't mind, share the cost?

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Well, it started when I called for a mobile mechanic and the soonest I could get help was 30 Nov. The cost would have been $80 service fee and $90 per hour--I figured his repair would have cost me at least $400. That inspired me to take the unit out and troubleshoot myself because I had nothing to lose. I concluded that it had a bad fan wheel and a motor. That would have cost me about $150 and I still had an older unit. A new unit cost me $680 which includes tax and overnight shipping from Amazon. Was it worth it...I don't know...but I'm happy with the new furnace and I'm keeping the old one for parts.

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