Suburban Furnace making noise like an air compressor

WestPat · Jan 10, 2021

Hello,
This is an issue on a 2014 Gateway 3650BH. It has a Suburban AirXcel Furnace. I am not sure of exact model number. We are using the 5th wheel and considering buying from a family member. We have used the furnace briefly, and they never used it in the time they had it, since we are on the Gulf Coast, and it has been a summer only rig. When when we turned it on tonight, it worked well, then started making a noise as loud and obnoxious as an air compressor. Went outside, the vent was still venting warm air, but not as hot as normal, it also had a gas smell with it. We turned everything off, including the propane. When we restarted the furnace without the propane on, it made the same horrible noise. Turned it all off, then turned it back on and the same noise with the warm air blowing out of the plenum. Turned off again. It is a Suburban AirXcel furnace. I could not see the exact model number. We r calling the local RV repair outfit in the morning to see what is wrong. My sister-in-law's family never used the furnace in the whole the whole time they have owned it. We are still interested in buying the 5th wheel, since the furnace was never used, it may have deteriorated over the years. If the whole unit has to be changed, would anyone recommend just changing it to a Cheap Heat stand alone system. The rig will not be used for boondocking since it is so large, and we have a generator with a 50amp plug large enough to power the whole unit.
Thank you for any comment and advice.
David West

LBR · Jan 10, 2021

WestPat said:
Hello,
This is an issue on a 2014 Gateway 3650BH. It has a Suburban AirXcel Furnace. I am not sure of exact model number. We are using the 5th wheel and considering buying from a family member. We have used the furnace briefly, and they never used it in the time they had it, since we are on the Gulf Coast, and it has been a summer only rig. When when we turned it on tonight, it worked well, then started making a noise as loud and obnoxious as an air compressor. Went outside, the vent was still venting warm air, but not as hot as normal, it also had a gas smell with it. We turned everything off, including the propane. When we restarted the furnace without the propane on, it made the same horrible noise. Turned it all off, then turned it back on and the same noise with the warm air blowing out of the plenum. Turned off again. It is a Suburban AirXcel furnace. I could not see the exact model number. We r calling the local RV repair outfit in the morning to see what is wrong. My sister-in-law's family never used the furnace in the whole the whole time they have owned it. We are still interested in buying the 5th wheel, since the furnace was never used, it may have deteriorated over the years. If the whole unit has to be changed, would anyone recommend just changing it to a Cheap Heat stand alone system. The rig will not be used for boondocking since it is so large, and we have a generator with a 50amp plug large enough to power the whole unit.
Thank you for any comment and advice.
David West

IMO, the first thing to check is the fan motor.

Even tho is has "0" hours of run time since new, the motor shaft could have an elongated output bushing from weight on it, age, and heat. When an electric motor output shaft runs in an elognated hole, it can vibrate severely, and could make that chattering, "air compressor" sound.

WestPat · Jan 10, 2021

I hope it is along those lines. It was still blowing some warm air out of the vents, but not nearly as strong as when the noise wasnt present. I hope to have someone come out in the next two days. Maybe it will be an easy fix.
Thank you,
David

mlburst1 · Jan 11, 2021

If the outside vents don't have a screen covering of some type over them, it's quite likely that mud daubers or similar pests have built nests on the fan blades or cage. A good cleaning may be all that is necessary.

Flick · Jan 11, 2021

mlburst1 said:
If the outside vents don't have a screen covering of some type over them, it's quite likely that mud daubers or similar pests have built nests on the fan blades or cage. A good cleaning may be all that is necessary.

Absolutely, my money goes on the bet there’s a mud dauber that will be mad at you!!

centerline · Jan 11, 2021

its my opinion that it needs a good cleaning, inside and out...
i think you have cobwebs in the flue, which is a common problem..... one would think these would burn out with the slightest flame but they dont...

RV water heaters are prone to this also....

a mis-aligned orfice can also cause the flame to surge.... while your in there checking for alignment and cobwebs, use an air compressor to blow the flue out, as there may be soot and particles in there that are a by-product, that only serve to insulate the heat exchanger from the flame....

inside the rv, at the furnace housing where the air intake is, with the furnace fan running on high, use the air compressor hose to blow into the heater intake from different angles, to remove all the accumulated dust and debris from the fan and intake area... afterwards, if heat is being produced from the heater, you will have a smell of dust and debris drying out as it gets disturbed on the heat exchanger of the furnace... this is normal if the heater needed cleaning, and will go away in about 10 minutes....

ive seen heaters get so full of lint, dust and debris that a piece can fall loose and get caught in the fan, upsetting the balance and making a racket as it runs....

WestPat · Jan 11, 2021

I have someone coming to look at it Wednesday. If it turns out that we will have to replace the furnace, then I believe I will just stay with my parents for a while and order a CheapHeat replacement unit. The 5ver wont be going any farther north than Nashville, and shouldnt have more than a weeks worth of below freezing weather while it is occupied.
I would be interested to hear any thoughts on that product, and switching over to that.
Thank you,
David

centerline · Jan 11, 2021

WestPat said:
I have someone coming to look at it Wednesday. If it turns out that we will have to replace the furnace, then I believe I will just stay with my parents for a while and order a CheapHeat replacement unit. The 5ver wont be going any farther north than Nashville, and shouldnt have more than a weeks worth of below freezing weather while it is occupied.
I would be interested to hear any thoughts on that product, and switching over to that.
Thank you,
David

whats the problem that has caused the need to replace a furnace that you said hasnt been used much?.... these furnaces last a long time, and I doubt it needs replaced unless it has been used hard for several years...

as for the CheapHeat system, if you mostly plug into shore power, its a great unit, that is cheaper and more efficient than using propane... but it has to be used with the existing propane furnace.
if the fan function doesnt work in the existing propane heater, the CheapHeat add-on unit wont do you any good...

danemayer · Jan 11, 2021

centerline said:
whats the problem that has caused the need to replace a furnace that you said hasnt been used much?.... these furnaces last a long time, and I doubt it needs replaced unless it has been used hard for several years...

as for the CheapHeat system, if you mostly plug into shore power, its a great unit, that is cheaper and more efficient than using propane... but it has to be used with the existing propane furnace.
if the fan function doesnt work in the existing propane heater, the CheapHeat add-on unit wont do you any good...

I think there is a plug compatible electric only replacement from CheapHeat.

LBR · Jan 11, 2021

centerline said:
whats the problem that has caused the need to replace a furnace that you said hasnt been used much?

Post #1 pretty well explains the concern, I thought.

centerline · Jan 12, 2021

LBR said:
Post #1 pretty well explains the concern, I thought.

not at all...
post #1 says the heater was never used but a few times.... how does this explain why it needs to be replaced?.. just because its making a noise doesnt mean it needs replaced, but i would agree that a servicing of it would be in order....

I have worked on many of these propane RV furnaces, and its very seldom that one is ever used enough that it needs to be replaced, BUT, sometimes one just wants to upgrade, or the repairs are on the expensive side and it may make more sense to replace it to a newer version, but when someone says its making a noise, and the repair guy who hasnt even looked at it yet is claiming it needs to be replaced, I would strongly suspect the repair guy is throwing the customers money at a problem that may not exist... a good cleaning is usually all that is needed if the unit is producing heat, but is only noisy..... and the flue is the first place i would look if the flame is surging and sounding like a compressor running... and then the blower fan, as I have seen stuff get caught in the blower fan causing an imbalance that will make a racket.

danemayer · Jan 12, 2021

Could also be a problem with the blower assembly. A few have reportedly had vanes break, creating quite a bit of noise. But not too difficult or expensive to replace.

TravelTiger · Jan 12, 2021

If you are committed to replacing with CheapHeat electric only solution, be aware that unless wired specifically to run on both, they run on only 30amp -OR- 50amp. This may limit you if you cannot find the appropriate electrical connection.
Be aware that CheapHeat uses as much electricity as an AC unit. You cannot run “everything” while running CheapHeat, so you have to be mindful of your amp draw.

Also, the original furnace can run with battery and propane — at least for a while — if there’s a power outage or you’re stopped somewhere without electric hookups, so adding CheapHeat to an existing (properly running) furnace gives you the best of both worlds.

Flick · Jan 13, 2021

TravelTiger said:
If you are committed to replacing with CheapHeat electric only solution, be aware that unless wired specifically to run on both, they run on only 30amp -OR- 50amp. This may limit you if you cannot find the appropriate electrical connection.
Be aware that CheapHeat uses as much electricity as an AC unit. You cannot run “everything” while running CheapHeat, so you have to be mindful of your amp draw.

Also, the original furnace can run with battery and propane — at least for a while — if there’s a power outage or you’re stopped somewhere without electric hookups, so adding CheapHeat to an existing (properly running) furnace gives you the best of both worlds.

Running your furnace without 110 is a very good point to make because I would think most don’t know it’s possible. When we do this, we just need to keep a very close eye on available battery power due to heavy drain from the fan running, probably around 5+ amps (just guessing).

LBR · Jan 13, 2021

centerline said:
how does this explain why it needs to be replaced?..

No one said it **needs** to be replaced except you, however the OP mentioned **if it needs** to be replaced once.

WestPat · Jan 13, 2021

danemayer said:
Could also be a problem with the blower assembly. A few have reportedly had vanes break, creating quite a bit of noise. But not too difficult or expensive to replace.

After initial inspection sir, you are the winner!
There are three vanes broken on the rotary fan. Also he said that it felt a little loose on the shaft. I told him that I would be okay with replacing the whole blower unit since it it is seven years old.
Otherwise the insides were very clean. The vents on the outside cover has fine mesh screens, and I think that has helped keep the critters out.
I will update with a final verdict and cost once the work is done.
David

- - - Updated - - -

Travel Tiger and Flick,
Thank you for the additional info and perspective on CheapHeat.

centerline · Jan 13, 2021

LBR said:
No one said it **needs** to be replaced except you, however the OP mentioned **if it needs** to be replaced once.

you are correct... I missed the "IF" part of the statement, but either way, I stand by my comment that "it is very unlikely that it needs replaced", and that some "self proclaimed" mechanics will spend the customers money carelessly, hoping it solves the problem....

LBR · Jan 13, 2021

centerline said:
I stand by my comment that "it is very unlikely that it needs replaced", and that some "self proclaimed" mechanics will spend the customers money carelessly, hoping it solves the problem....

I totally agree.

2 weeks ago was the first time our 4.5 year old furnace hiccuped.... fan would start, then stopped with no ignition. After troubleshooting 12V and propane systems and finding everything in order, I knew it was the sail switch or circuit board. Pulled the outside cover and disassembled the fan shroud to access the switch to test....opened it up and found 4 years of our several fur-babies' hair balling up the micro-switch....lol....imagine that..

Put a reminder in my phone calendar of "Furnace Maintenance" in 2 years!

Suburban Furnace making noise like an air compressor

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