Poor Furnace Performance

[TLScout]

Originally Posted by ChuckS

Have you used a thermometer and measured the output air temp at each floor duct yet?

No--but I will do that tomorrow.

Originally Posted by ChuckS

I would check the air duct from the furnace plenum to the floor duct for kinks, etc

I've already done that. There seems to be proper airflow at all of the registers--it just isn't very warm.

Originally Posted by ChuckS

My stairwell ducts have been blocked off for the ten years I have owned my unit .. at 0 degrees outside temp my furnace will run you out of the unit if you set the temp above 65 degrees..

I set our furnace at 55 to 58 degrees at night when in cold weather and it runs a few minutes here and there to maintain the set temp.

YMMV

That's consistent with how my old travel trailer performed. As I posted originally--I'm certainly not seeing that kind of heat coming out of the furnace or registers in this one. It's frustrating. I can heat and maintain the entire coach at 70 degrees F using my 1500W space heater (when connected to shore power) but the propane furnace can't keep up.



I'm going to install an air return in the pantry--which sits just next to the furnace air intake. If that doesn't work--then I guess I'll have to take it back to the dealer after my Christmas trip and let them troubleshoot it. I like to boondock during the early spring and late fall--so I really need the propane heater working correctly.

[jasin1]

Originally Posted by TLScout

Thanks for finding this video!! That is certainly my floorplan and rig--but I do NOT have the under-stair return air vent as shown in the video. I've looked throughout the coach and there is no return air vent in my camper. I'm starting to think that they "forgot" to install it. Right now--the only way that air gets back to the furnace from the living area is through gaps in the floor/walls and drain openings.

Have you tried to push on the carpet under the stair treads to see if they cut the holes out but left the grills off? …i wouldn’t cut a hole in the floor or you will likely void any structural warranty…take it to the dealer…but also check for precut holes behind the carpet

[TLScout]

Originally Posted by jasin1

Have you tried to push on the carpet under the stair treads to see if they cut the holes out but left the grills off? …i wouldn’t cut a hole in the floor or you will likely void any structural warranty…take it to the dealer…but also check for precut holes behind the carpet

I checked. Everything is solid behind the carpet on the stairs.

I won’t be cutting a hole in the floor. If I add an air return, it will be thru the thin wallboard under the bottom shelf of the pantry. That wall sits right next to the furnace on the intake side.

[sourdough]

So let's think about this for a minute; the air is not hot enough. You said the air flow seems adequate which eliminates the need of air from a return air vent, sort of. The plenum has been checked with no openings, loose hoses etc. so the "heated" air from the furnace is being routed properly to the vents. The air coming out isn't hot...or warm enough. Is the furnace operating properly? Have you checked the model to make sure it is in fact one sized for the trailer? Silly I know but starting at the bottom.

After that as was suggested measure the temps at the vents. I assume they won't be too warm based on your issues. If not, and the furnace is correct, "and operating properly", the only thing as I think you are leaning to is that it's constantly pulling in cold air vs warmer cabin air to heat. The problem I have with that is that I block my stair vents (about 80%) to keep the cold from underneath coming into the trailer and my furnace will literally run me out of the trailer in 20-30 degree temps. I'm still wondering about sizing (which I would never have doubted in years past), efficiency etc.

[Old Mustanger]

Any chance your air return is behind the pantry door? That is where it is in mine, with a vertical register that when removed leaves an opening large enough to pull the furnace out through. (I do not have any cutouts in my steps.)

[TLScout]

Old Mustanger—No. unfortunately there isn’t a return in the pantry (or anywhere else).

[jasin1]

I agree with John and Danny and a few others regarding temp readings….. you should take picture of the nameplate info for your furnace and establish what model you have.

Find out either thru dometic or it could ( should) be on the spec plate or owners manual of the designed “ temperature rise” of that particular furnace.

take temperature readings of the return air at the furnace…the supply air at the furnace and see if the temp rise falls in line with specs…..take these as close to furnace as possible

Have someone verify the gas pressure at the furnace and make sure that’s within design specs…could have a bad pressure regulator at the tanks…i don’t think they are adjustable on rvs ?

Get all of this info together or just drive to the dealer and turn the furnace on and have them come out and see for themselves with a thermometer

i don’t think i’d start modifying things without a quick trip to the dealer to check or even walk thru another trailer to verify

rv manufacturers already barely approve any warranty work so i wouldn’t give them any ammo to deny future claims

[Fishhawk1650]

I have a 2023 23MLE and it has return ducts on the steps and no carpet. The only carpet is around the bed, otherwise no carpet anywhere. The furnace works like a champ and has no issues keeping or maintaining heat.
Maybe you got an earlier build? I believe my build was March 2023.
Another difference is my floor registers are not the new plastic fancy ones but are the typical metal type cheese grater type.

[tallen]

any luck finding the return air?