Mod Description:

As odd as it is, sometimes an RV manufacturer will neglect to install a furnace vent where you need it most, like in the bathroom or bunk house. It’s no fun making that 2-in-the-morning trip to a freezing bathroom. This mod is about adding that missing furnace vent using one of your unused furnace air distribution box outlets.

Mod Difficulty:

Suburban furnace housing with vent ducts

Dryer duct hose attached to furnace duct collar

Dryer duct routing through underside of lower bunk bed

Entrance of dryer duct to the bathroom

Muffin fan installed inline with vent register

Vent register installed and painted to match

The furnace air distribution box, as its name implies, distributes the heated air pushed in to the box by the heater fan. Metalized hose is attached to a duct collar which is attached to the box, and this hose runs to the heater registers in your RV. In most RVs with this type of furnace, there are always a few outlets that are unused and blocked off with a removable duct plate.

So we start by removing the furnace grill and taking a look around the air distribution box for an unused outlet. For those furnaces that force the air out the bottom of the box to floor-mounted registers, it may be a tight fit between the box and the compartment. In this case, patience is a virtue as removing the blocking plate and adding the duct collar can be a bit trying, but it can be done!

At this point, you should make sure you have a duct collar, 4″ dryer duct hose long enough to run to where you want the new heater vent, a few 4″ clamps, a heater register, and a 4″ hole saw, all of which can be purchased at your local RV parts store and/or local home improvement store.

After you find an unused outlet, remove the duct plate and replace it with the duct collar. This collar twists in to the outlet and can also be secured using a single sheet metal screw if you have the room to get a screwdriver in there. Now look around the compartment and see how you will route the dryer hose to the heater register. If you’re lucky and you have some cabinetry running the length from the furnace to where you want the register, you can just route the hose through the back part of the cabinets. If not, you will have to get creative.

Attach the hose to the duct collar using a 4″ clamp. Make sure you slide the hose all the way on to the duct collar. Otherwise, as you tighten the clamp, you will just crush the hose. Route the hose through the cabinetry to where you will mount the new register. Now using the hole saw, carefully cut the register hole taking care that there is nothing behind the hole, like wiring or plumbing. Reach in and carefully slide the hose through the hole. Attach the hose to the register using another clamp. Slide the register in to the hole, secure with screws, and now you have heat right where you need it!

If the length of the hose to the new register is longer than 15 ft. or there are many bends in the hose to accommodate routing, you can add a small muffin fan at the register to assist flow. Simply wire the fan’s power to the heater’s thermostat so it will automatically turn on and off with the heater’s fan motor.

ModMyRV recommends these parts for this mod:
Broan-NuTone 124 750/1500W Register Heaters
Zodi 12-Volt Hot Vent Fan
Dryer Vent Hose - 25 ft. Metal

7 Comments For This Mod

1. jmt (March 3rd, 2009 at 11:19 pm)

   Pretty easy mod especially when you need heat.
2. Bob Vaughn (March 10th, 2009 at 3:33 pm)

   My heat ducts run thru the floor….Only one of my ducts exits out the wall and that is the one that puts out heat in front of my front door….the one I had to make my trash bin sliding shelf to clear…In this photo you can see the heater hose in the back of the cabinet
   http://home-and-garden.webshots.com/photo/2179224090090646914zEeygp
3. sundancer268 (April 12th, 2009 at 12:09 pm)

   I replaced all the 4″ flex duct for my furnace with metal duct work and elbows, this really made a difference on the heat out put and even spread of heat. I also insulated the duct work and now the heat goes where it is suppose to. Before anything in the lower cupboards were being heated quite well and we were freezing in the back bed room. It was a lot more work but none of the new metal duct work can be crushed and being smooth inside the air flow is much higher. Just my 3 cents worth (Inflation).
4. ModMyRV (April 12th, 2009 at 3:15 pm)

   That’s a great idea sundancer! I plan on doing the same to the 3″ flexible duct hose I ran around 15 feet. That’s why I installed an inline muffin fan to help pull some of the air lost by the rough interior of the ducting. It helps but it’s not where I would like it to be. Thanks for the 3 cents!
5. Travis (October 29th, 2009 at 6:45 pm)

   I added a AC vent in my back sleeping aera. They had it in the bathroom and the beds got too hot. Not any more. Easy MOD to do.
6. ON-A-ROAD (February 8th, 2010 at 8:13 am)

   And I thought I was the only one who thought of this! For those of us with 5th wheels the heat duct ends where the bedroom slid starts. (on my 2005 Carriage its that way anyway). So I took off the basement panels to access the heating ducts. I put a T on the forward vent and ran it forward past the bed.

   I ran the ducting through the front storage area using the flex duct. I also put a T on one of the ducts going to the living area and ran a vent into the potty room. The vent in the potty room was a smaller round style. Works great, awesome mod!
7. aquastell (June 28th, 2010 at 10:11 pm)

   hahaha… I found out that my Winnebago had a heat vent running under the bathtub and into the build in drawer stand in the bedroom. Simply brilliant. My sock drawer was plenty warm in winter! um, yeah, I moved it out of the drawer.

Let's hear your comments about this mod!