Just curious - cold rear bathroom

I was able to run a 4" duct from my furnace under the cabinets to a small round vent register I placed on the stub wall the tub mounts to. I bought the register at a local RV place, and it has a variable damper in it so I can shut it off. The duct is semiridgid metallic dryer vent hose, and the collar that mounts it to the Atwood furnace I bought off Amazon. It works really well to keep the bathroom comfortable without robbing the other ducts of much air flow.

Check your emergency window. They work themselves loose but not always enough to fall out. I felt cold drafty air in back and finally found it coming from bottom of escape window.:R

We had inadequate heat output from our furnace in the kitchen area, even with outlet only about 4-5' from the furnace. The 4" duct goes from the furnace down into the underbelly space and back up to an outlet in the kitchen area. The duct they use is similar to that used for clothes dryers and has a rough wall that restricts flow and was also uninsulated under the floor. I pulled it out, replaced it with smooth wall semi-rigid aluminum duct (as in photo below and available at HD) and wrapped that with a 1" thick foil-backed blanket of insulation and re-installed the duct. I was able to do this from above but longer runs would require re & re-ing the underbelly material. IIRC, the overall length of the duct was around 10' overall.

This mod made a huge improvement in heat output. Our outlet in the bedroom was always on the too-warm side and was fed with a 4" duct. I replaced that with a 2" duct and now the bedroom and kitchen/living are both comfortably warm at about the same temp.

However, we rarely use the furnace now because I installed 3 permanent electric heaters that do an excellent job of heating the trailer. When it gets close to freezing, we use the furnace tho. so some heat will get into the underbelly space and keep the tanks from freezing plus make the floor warmer.

A photo of the new duct with insulation before installation is also below. Fishing the new duct through the joist spaces blind from above was not fun...

If you could live with the extra current draw, an electric recessed wall heater of 250-500 watts *might* be an option if you know how to run wiring concealed in walls and ceiling. King makes a fan-forced wall heater with adjustable tap settings starting at 250 watts.

Rock - no, I doubt my el-cheapo 4Wind has a heated sewer tank but I will check that end-duct in the bathroom. Or will proceed with plugging all those dust-collecting, me-tripping-over registers in the floor, since I'm not using them.

Steve - yes, I could add some fans to distribute heat more uniformly. It's not that the cold-ish bathroom bothers me much, just curious about the source of the heat leaks. Must be the combination of bald spots in walls and under the bathtub.

Almot,

A couple ideas:
- Simple: Open the bath ceiling vent and leave the door open. Rising warm air will work it's way into the bathroom to escape.
- More work, but better results.....if your floor plan allows: Put a couple computer fans, controlled by a simple thermostat, in the main cabin somewhere that they can blow air into the bathroom. I put mine under my fridge and they blow air under the under the tub (keeps the plumbing from freezing too),but you could put them above the door too. I then put a small grill on the side of the tub to let the air out and into the bathroom (if above the door, no need to do anything other than another grill). Still need to leave the overhead vent open.....not a bad idea if you are running a cat heater anyway.
The above works well for me down to -18 F.

p.s.; opening the door and vent, and turning the bath fan on a few minutes before you go into the bathroom (as in to take a shower), really warms it up quickly if your cabin is warm.

Does your Four Winds have enclosed sewer bay?

albiet not a TT but on my MH Four Winds they took the bedroom heat duct and 'split' it. Half goes to the bedroom and the other half goes to the sewage bay (what I call Polish heated sewage tanks).

So my bedroom is always cold. It's an end run duct and 1/2 open to the bay. So when it's cold outside and I am not using the heat cold air actually comes back in.

3:16 pm...I'm not using furnace.
3:42 pm...run 5000 BTU cat heater on Low for an hour or so,

Outside temps in the night are 50F and up.
I run 5000 BTU cat heater on Low for an hour or so, if it gets too cold before bedtime. The heater is near middle of the trailer, and bathroom is still the coldest place, with or without the heater.

No kidding, it's just the coldest room. I think they've completely skipped that pink insulation wool in the back wall. Or there is no 3/4" floor under the bathtub.

Then turn the RV 180 degrees and the bathroom area will warm up.

Almot wrote:
No, not a duct air flow issue. I'm not using furnace. It's just cold at the rear end, have to close bathroom door in the night. My forehead usually reminds me to open it :)

Your bath gets cold and the furnace isn't running :?
What are the outside temps?