Heat duct size

mrekim wrote:
I have a front bedroom TT. The duct work that goes to the bedroom is small - maybe 1" it doesn't flow any air to speak of. It's the same size as the duct that terminates under the TT for the "heated" holding tanks. Way smaller than the 3 ducts that terminate in the rest of the living space.

Here's the floorplan:



Heater is under the refer. Larger ducts terminate from sink towards rear, sink towards dinette and Micro/Stove facing dinette. The very small (1" no more than 2") duct terminates under the front Ward on the passenger side facing the rear.


Is such a small duct here common practice?

I have a very similar trailer as you (well minus the bedroom slide, the previous version)

In my trailer ALL the vents are the std. 4" ductwork. In my case, the issue was that the std ducting (thin mylar coated wire frame ducting) lost lots of heat going to the living area. So I just replaced ALL the ducting with 4" rigid ducting and then wrapped it in foil insulation. WHAT A DIFFERENCE!!!

At some point they seem to have added a 1" or 2" duct vented into the underbelly to heat it.

Also to watch (listen) is if the burner cycles on and off during the heating cycle.
This would indicate poor airflow causing the high limit switch to open.

I spoke to the dealer. The official factory test to determine if there's an air flow problem is to put the fan on and see if a tissue moves. So it's all good as far as the factory is concerned.


We'll see how the winter goes. The suggestion for using small electric heaters is a good one that should work well.

My TT has a manifold which consists of 4x 4" exhausts: living room, kitchen, bathroom and bedroom. When heating, I get equal temps across the TT, no cold spots - great when the kids are sleeping with DW and I. Now when we are camping alone, there is no need to heat the whole TT, just the bedroom - then I use this: Sunbeam convection heater

Small, low-profile (easy to store) and with temperature presets. No noise since there are no fans, and with the door closed, heats the room quickly.

3.0charlie wrote:
Is this a floor duct, running in the basement?

Yes, well not a floor duct. It goes in the basement at the heater and terminates in a cabinet 6" above the floor.

dougrainer wrote:
Yes, that is normal. The reason for the smaller ducts is to limit a large volume of hot air where it is not needed. You sleep with sheets and blankets. You would get too hot if they ran larger ducts.

I was thinking the exact opposite. When I'm sleeping I want to set the living area temp to 45 degrees or something and close the bedroom doors to keep that area warmer. The doors could be opened some to keep it from getting too hot. What I need to do now is to heat the living area to 65-70 degrees and keep the doors open all the way in order to keep the bedroom at 55-60 degrees. So I use way more battery and gas to keep the bedroom comfortable vs a large vent.

Maybe I'm thinking about this wrong?

As a test, I was able to block of the bedroom vent with 5 post-its. They kept it closed for at least 10 seconds with the blower running.

In any case, I guess this means that it's probably not a factory mistake and I can't expect it to be "fixed" under warranty. It's something I would need to do on my own.

dougrainer wrote:

They also do this for the bathrooms also.

A duct in the bath would have been nice too. The bedroom duct size is just about right for the bath. 

dougrainer wrote:


The more heat(volume) going to the tanks is less heat to the inside of the RV. If they run larger ducts to baths and bedrooms, they usually install a duct grill that you can shut off or lower the volume of air. Doug

Yes, I understand the small duct going to the tanks - It's probably pretty short too so there's less restriction.



I think the problem with the bedroom is that it's 1" duct at 10 feet long (or more) with who know how many bends. Since they all come out of the same manifold I think most of the air is flowing in the much shorter/less restricted ducts. It sounds like I won't win a battle asking for 4" ducting under warranty.

smkettner wrote:
Fairly common for ducting to be poorly installed with poor joints, compressed tubing, restrictive routing, or just disconnected.

Wonderful, well I guess that also means the warranty department is used to paying for having it inspected.


So, maybe I asked the wrong question. What's the best way to keep the bedroom comfortable without having to heat the rest of the living area?

Fairly common for ducting to be poorly installed with poor joints, compressed tubing, restrictive routing, or just disconnected.

Yes, that is normal. The reason for the smaller ducts is to limit a large volume of hot air where it is not needed. You sleep with sheets and blankets. You would get too hot if they ran larger ducts. They also do this for the bathrooms also. The more heat(volume) going to the tanks is less heat to the inside of the RV. If they run larger ducts to baths and bedrooms, they usually install a duct grill that you can shut off or lower the volume of air. Doug

Is this a floor duct, running in the basement? I was looking at mine yesterday actually, since a mouse decided to chew on the insulating material. The duct on my Kodiak is ~4" dia., same as the kitchen and living room floor exhausts.