Improving the heat in 5th wheel.

I have a 2013 Sandpiper 365saq. It's 43' long has 4 slides with 9' ceilings and the 35k btu heater is dismal at best. The warmest it could get when it was 30degrees outside is 60 degrees inside. The camper has the upgraded insulation package. I called Forest River and they said sorry but that is all I should expect because it's not a 4 season camper.
My old 1995 29' would run us out even down to zero degrees. The air coming out of the vents just didn't seem to blow very hard.

I decided to do some testing. I bought a handheld wind meter and checked my vents to see how hard they blow. I have 4 vents in my camper. 1 in the master and upstairs bathroom. They are both fed by a duct that two hoses from the furnace connect to. I have a vent in the main room and the kids room, these are also fed by another duct and 2 other hoses from the furnace feed this duct. My main concern is heating the kids room.
If I run the furnace the way it was designed the 2 upstairs registers flow 5mph. The main room flows 4mph and the kids room flows 3.5mph.

If I close all the vents but the kids room it will flow 8mph. I then checked to see ho hard the hoses will blow without the duct. I added a 5th hose to the furnace and put a round register on it. It will blow 12mph and the kids room maintained 8mph.
So it seems the ducting is very inefficient in my camper.
I decided to add a register to one of my air intake vents under the stairs to help heat the main room while still providing the most heat to the kids room.
I cut the stock register to accept the new round register.

Here it is installed in the register.

Here is the hose routed under the stairs.

Here is the octopus of hoses from the furnace.

I can now sit on the couch and feel the air from my new vent, and the kids room feels good. The upstairs gets plenty warm just from the heat rising.

I do have one question for the board. My furnace burner cycles on and off while running. I haven't timed it but it seems to stay lit for about 10 minutes and then the burner will shut off for a couple of minutes and then relight. I understand the furnace is reaching it's high heat limit while running my question is should it do this? I never heard my old furnace do this while it was calling for heat. I would think that the furnace should stay lit if it is moving enough air thru the furnace, btw it does the same thing with all the vents open.

Thanks

M_GO_BLUE1
Explorer
Jun 19, 2013
That new vent you installed is very close to the thermostat (if that is thw thing with the cover off)...maybe the heat from the new vent is rising quickly and the thermostat sense it and turns off before the room reaches the preset temp...
jcthorne
Explorer
Jun 19, 2013
The fact that your furnace burner is shutting off on high limit is proof you have air flow restrictions. It should not operate anywhere near the burner cut off temp. Its likely all that dryer duct used for the vents that is the problems but adding a vent or two may help as well. Real flex duct like used in home hvac systems may help some and be fairly easy to install.
SpencerRB
Explorer
Jun 18, 2013
After our first full time winter, including 3 months in Breckenridge, CO, I learned quite a bit about the heating system in these big 5th wheels.

- The furnace system is extremely inefficient, and expensive to operate. They are only 60-80% efficient, plus they don't allow much zone control other than vent closures.

- Factory furnace ducting is horrible. I upgraded much of my trailer to semi-rigid. Rigid would be best but a pain in the butt to install.

- Long run ducts (such as your back room, or my garage) need a booster fan to get any sort of decent flow/heat to them. I installed a 4" 12v Bilge Pump, which really flows the air. Bilge Pump

- We found small 1500 watt space heaters connected to Lux Win100 thermostats in each room to be the best solution for primary heat. Allows us to run heat only in rooms we need it rather than heating an entire 42 ft trailer overnight. 100% efficient, plus don't produce tons of moisture like propane furnaces. We also found the cost per BTU to be about half the cost of propane when we were paying electric at campgrounds. If you aren't paying electric, then this is a no-brainer. Additionally, we would set the furnace as a backup in case the electric heaters can't keep up.

- If you aren't hooked up, then the space heaters aren't viable. In this case, I'd look at vent-less catalyst or blue flame heaters.
JiminDenver
Explorer II
Jun 04, 2013
The tubing used as duct work is creating a huge amount of turbulence and slowing the air flow down. That in turn can cause the fan to not move enough air allowing the furnace to get too hot and the burner to shut down until the fan reduces the heat level.
Helper fans at the end of the ducts may help but replacing with a smooth walled duct would do the best.
Retired_JSO
Explorer
Jun 03, 2013
We had very much the same problem with our 2004 Sandpiper. I solved the problem by replacing the floor registers with those bought at a home improvement store that allowed me to slightly close the register. The real problem was forest river had installed an under belly storage vent so large, most of the heated air was going into the basement. Duct tape fixed that.
RoyB
Explorer II
Jun 03, 2013
There is an alternate source of heat that might help out to supplement your propane furnace.

This is the concept...

I have been looking into using this idea to actually replace my propane furnace in my OFF-ROAD POPUP. The propane heater is way to much heat for the popup, has its unique smells, makes a horrible noise, and the 12VDC FAN runs down my batteries in a quick order.

My concept might look something like this using PEX lines from LOWES.

How this might help your situation would be to run baseboard hot water registers around the walls , in the bath room and other floor level locations... Some of these registers can be equipment with small axial type fans... The hot water comes from the 6-gallon hot water heater. Might be something else to investigate to get more heat around the floors. Using the Hot water heater as the source makes this work both at shore power locations as well as running off your propane to heat up the water and batteries to run the fan if needed camping off the power grid.

You could have multiple zones doing this...

Might be worth some reading on the internet. ALot of big motorhomes are using this type of clean heat.

Just some of my thoughts
Roy Ken
mpierce
Explorer
Jun 03, 2013
I would think that if the burner is cycling on the high limit, you either need more hot air ducts, and/or return air. I think you are short on airflow.
Jimf1234
Explorer
Jun 02, 2013
I plan on getting some better hose to remove the kinks and twists. Every time I work on this it amazes me how cheaply they put these together.
ferretgrandpa
Explorer
Jun 02, 2013
My 08 Flagstaff had the furnace badly installed, dealer had to redo the plenum area, made all the difference in the world.
Also remember that every turn and kink in the ductwork cuts the flow down.
Jimf1234
Explorer
Jun 02, 2013
Nope they don't offer a larger furnace. I was not able to test nor did I think I needed to check the furnace. For most parts of the country no one even knows there is a issue. It seems most people that actually use there campers in cold weather are fulltimers and they use electric heaters to supplement there heaters. I was actually thinking of installing a second furnace because the dealer said that is what they are now doing with the bigger campers/ toyhaulers to have enough heat in the winter. I understand these campers are built with the absolute minimum of everything. I did get the 2nd ducted a/c unit to help with the undersized a/c. This floor plan is the one they wife had to have.

I see your from Oregon and my dream rig would be this floorplan built by Northwoods. It would probably weigh 20k pounds though.

I looked at alot of campers and they all have issues if you really start to look. I can fix alot of things, but floorplan is out of my realm.