Furnace fan self-destructed at 4:45 AM today in 35-degree weather

[NXR]

It's only our fifth trip so I guess we should be expecting failures on a 2020 coach by now, eh?

Last night the temperature dropped to 35 degrees where we’re at. Around 45 degrees last evening the heat pumps shut down as expected and the propane furnace fired up. Everything was nice and toasty.

About 9 PM the furnace started making an intermittent ticking sound that started a few minutes after it fired up. It was not loud but occasionally it got louder. We went to bed about 12:30 AM and the ticking noise was more consistent and somewhat louder.

At 4:45 AM this morning we were awakened by very loud noises that sounded like the furnace was self-destructing. I shut both thermostats off but the noises continued until they suddenly ground to a halt. It sounded like metal-on-metal. I removed the inside furnace grill, the plastic black one below the fireplace, but saw no damage and felt no indication of heat and smelled no smoke.

I decided to disconnect the furnace power and located a blown 15-amp fuse on the foot of the bed marked “FURNACE REFER”. I thought “No way they did that” but yes, they did.

Forest River wired both the furnace and the Norcold refrigerator to the same 15-amp fuse and now the refrigerator was also dead. I had a 10-amp fuse inside so I installed it, knowing the Norcold only requires a 5-amp fuse. The refrigerator fired up and stayed powered on.

We ran the fireplace on High for the remainder of the night and the inside temperature got down to 65 by 8 AM from 72 at 5 AM.

This morning I removed the furnace exterior panel and saw that the plastic squirrel cage fan has partially disassembled itself. I also flipped the furnace power switch to Off so we can run the Airxcel heat pumps when it warms up later today.

Ray

[Mike223]

Bummer.
Mike

[NXR]

Why am I thinking that the dealer will find construction debris inside the furnace that caused the failure? I'm just glad it happened now and not on a trip we have planned for November.

Ray

[NJKris]

Go pick yourself up one of those Buddy heaters for now. Keep ya warm! My big buddy heater will heat up any RV

[NXR]

How long will it last with a 1 lb propane bottle?

I've got two 1,500 watt electric heaters sitting in the basement at home and I'm betting one of them will be moved to a different "basement" later this week. That should assure we never have a heating failure again.

We were thinking about heading home early because its supposed to be 41 tonight and 35 tomorrow night before it warms up. But we decided to stick it out so we can see what else we need to haul along, like extra blankets.

Ray

[MR.M]

Originally Posted by NXR

How long will it last with a 1 lb propane bottle?

I've got two 1,500 watt electric heaters sitting in the basement at home and I'm betting one of them will be moved to a different "basement" later this week. That should assure we never have a heating failure again.

We were thinking about heading home early because its supposed to be 41 tonight and 35 tomorrow night before it warms up. But we decided to stick it out so we can see what else we need to haul along, like extra blankets.

Ray

What brand furnace ? I'm guessing a atwwood dometic ? i've seen this issue before with the attwoods look for a metal replacement they make them you just need to search the model #

[NXR]

Originally Posted by MR.M

What brand furnace ? I'm guessing a atwwood dometic ? i've seen this issue before with the attwoods look for a metal replacement they make them you just need to search the model #

It's a Suburban SF-35Q. I'll ask the dealer if there is a metal squirrel cage version available.

Ray

[MR.M]

Originally Posted by NXR

It's a Suburban SF-35Q. I'll ask the dealer if there is a metal squirrel cage version available.

Ray

I've seen that happen with the atwood dometics . first time i've heard of it on suburban but as they say stuff happens . I would look for a metal replacement . haven't look for one to fit a surburban

[MR.M]

Originally Posted by NXR

It's a Suburban SF-35Q. I'll ask the dealer if there is a metal squirrel cage version available.

Ray

https://www.amazon.com/Suburban-3501.../dp/B004RCX7XE

[NXR]

Nice find.

Did you check the Question and Answers and see the one about whether it's metal or plastic? I posted it there about twenty minutes ago and already got two answers.

Ray

[dward51]

I always keep 2 of the small cube ceramic heaters in the trailer. In fact in the old Hilo we had back in the early 2000's, I heated the entire trailer with a ceramic heater with a squirrel cage type blower. But it was bigger than 2 small 1,500watt ones.

[MR.M]

Yes it's metal .

[NJKris]

NXR, don't forget those buddy heaters can be connected to a 20 lb tank via adaptor hose. Just run the hose out a window to a tank outside. This is what I do in my garage when I need to heat it at home.

[NXR]

Thanks for all of the suggestions, folks. i am asking the dealer to install a metal replacement even if it costs me a bit of money.

Ray

[Larry-NC]

Originally Posted by NXR

Thanks for all of the suggestions, folks. i am asking the dealer to install a metal replacement even if it costs me a bit of money.

Ray

SF-35 series furnaces have TWO squirrel-cage blowers, one on each end of a double-ended motor. One circulates outside air through the firebox and out the exhaust port. The other circulates inside return air through the plenum (around the firebox) and through the vents.

It would take very little additional labor to change both. If it were mine, I'd do that.

[NXR]

Originally Posted by Larry-NC

SF-35 series furnaces have TWO squirrel-cage blowers, one on each end of a double-ended motor. One circulates outside air through the firebox and out the exhaust port. The other circulates inside return air through the plenum (around the firebox) and through the vents.

It would take very little additional labor to change both. If it were mine, I'd do that.

I wonder if this one is different. The motor is mounted horizontally with a coach front-to-rear orientation. The two pictures I added are one from each side. So either both sides broke or it's one big one now. The pictures I saw of the replacement make it look pretty long.

Or there is a second motor and fan for inside circulation. I'll have to find a manual for this thing.

Thanks for the comment. If there are two I'll have both of them replaced.

Thanks!

Ray

[NXR]

I received a reply from Suburban and the use of the metal blower wheel will void the warranty on a SF-35Q so I will not be doing that:


Dear Sir;

We regret to learn of the issue you have encountered.

The composite wheel is certified for use in the SFQ furnaces. Installation of a metal wheel would void any warranty. You will need to have the service center install the correct wheel part number 350206.

<redacted>
Service Manager
676 Broadway Street
Dayton, TN. 37321
Office: 423 775-2131
www.Airxcel.com


Ray

[jcr59]

Originally Posted by NXR

How long will it last with a 1 lb propane bottle?

I've got two 1,500 watt electric heaters sitting in the basement at home and I'm betting one of them will be moved to a different "basement" later this week. That should assure we never have a heating failure again.

We were thinking about heading home early because its supposed to be 41 tonight and 35 tomorrow night before it warms up. But we decided to stick it out so we can see what else we need to haul along, like extra blankets.

Ray

We keep a 1500W heater in our TT at all times. Whenever we have shore power we use it instead of propane.

[nayther]

metal fan is too heavy for the motor they use, lighter weight reduces motor horsepower, less horsepower, less money.

[MR.M]

Originally Posted by NXR

I received a reply from Suburban and the use of the metal blower wheel will void the warranty on a SF-35Q so I will not be doing that:


Dear Sir;

We regret to learn of the issue you have encountered.

The composite wheel is certified for use in the SFQ furnaces. Installation of a metal wheel would void any warranty. You will need to have the service center install the correct wheel part number 350206.

<redacted>
Service Manager
676 Broadway Street
Dayton, TN. 37321
Office: 423 775-2131
www.Airxcel.com


Ray

Then get thew dealer to replace with another plastic wheel and when it goes out of warranty install the metal one