Furnance is making a rumbling noise

[rrdrtravelers]

We are in south Texas and starting to use our furnace for the first time since purchasing our unit in June. It makes a soft rumbling/thumping noise while running, almost sounds like distant thunder or a distant outside door closing. Its not loud enough to be bothersome? It heats great but just wonder if this sound is normal? It's also interesting to hear all the sounds the camper makes from in the front bedroom while the furnace is on - like everything is heating up and expanding in the basement below. I'm assuming these two sounds are unrelated? This is our first FW so never had the basement. Don't hear the "expanding" noise in the kitchen/living area.

[Ovair]

Not being able to hear it myself makes it difficult to be sure.
Try going outside and listening to the furnace exhaust. Seriously. Based on your description, it makes me think it might be blowing out and relighting continually. If that is the case, something is not right. If the exhaust sounds consistent and even with no "re-lighting" sounds, then the sounds you hear inside may just be caused by the heated air moving through the duct work.

[capucine]

For your rumbling sound I would check if the furnace does not touch something and causing some vibrations. Check also how it is securing on the floor. If all fails bring it back to the dealer. If the furnace is located under the bed like mine it can be disturbing while you sleep even if the furnace is okay. I hardly use the furnace. I bring my ceramic heater and I find it perfect to heat my trailer as long as the campground has electricity.

[rrdrtravelers]

Thanks for the tips. Will have the hubby check those things out. We do have ceramic heaters and should just use them in the bedroom because the electric fireplace in living room heats that area quite well. We bought our unit used so no warranty available. It's only a year old and we were told the previous owner only used it once. I'm thinking this is probably the first time furnace is being used.

[shelbyeeyore]

I just ran into an issue close to yours this July 4th weekend. A small bird had pull small twigs into intake hold (On my furnace it is the top hole) or the one Not mark HOT. I thought I had it all out and I fired the furnace to test. Pull what I couldn't see in around the fan wheel making noise. The furnace took cake of the cotton fiber in a hurry by burning it up. The good thing about these type furnaces is that they are all contained. Meaning, not much chance of fire in camper. Thinkt of it as a heavy duty muffler system that pulls air from outside and exhausts it right back outside without ever allowing any fire or fumes to access the inside of your camper. The fan blows over the outside of this muffler surface pulling heat into your unit. I plan to screen my intake and exhaust after this discovery. Hope it helps.. Shelbyeeyore Out..

[HVACretired]

Originally Posted by capucine

For your rumbling sound I would check if the furnace does not touch something and causing some vibrations. Check also how it is securing on the floor. If all fails bring it back to the dealer. If the furnace is located under the bed like mine it can be disturbing while you sleep even if the furnace is okay. I hardly use the furnace. I bring my ceramic heater and I find it perfect to heat my trailer as long as the campground has electricity.

I have attached a picture of where the flue pipe touched the side wall on the outside of the RV. If I wouldn't have don't caught it when I upgraded my Cedar Creek with the CheapHeat Electric heat add-on my RV would have burnt to the ground (Make sure nothing is touching).
Oh ya, I sent this picture to the factory. That was 2 years ago still waiting to hear from someone.

[RV Wizerd]

Larry Cavens here
The noise you are hearing is the main burner in operation, now there are two manufactures of these furnaces #1 Hydro Flame which is now made by Atwood the other is Suburban, I have found the Hydro Flame units are more noisy when the burner kicks in and yes it does sound like thunder which is normal/ whereas the suburban units are a little quieter, the reason why is the burner design/ which incorporates a air injection chamber that is fan forced, the air mixes with the propane gas then is burned, the only other thing that would cause noise is a unbalanced blower wheel which would vibrate the whole unit. If this is the case and is still under warranty the unit should be replaced if not under warranty get the blower wheel replaced as soon as possible or you will wear out the bushings in the motor and it will be more costly to repair