I fulltime RV, and in the winter, if the temp outside gets below 15F, my kitchen sink lines freeze, even with the heated, enclosed underbelly.Does anyone know a good product or method for adding a bit more heat to the underbelly that I can wire in in a more or less permanent way? I'd like to flip a switch on cold days and not worry about the matter any more.I have a spare 110V circuit since I switched to a tankless water heater, so I am perfectly ok with electric, but it needs to be safe, since it's not something I'm going to be able to monitor easily.Thanks!

Ultra Heat has 120V AC heat pads for waste/fresh water tanks.They also have 'heat insulation' for piping.Are you opening cabinet doors when temps drop that low so RV furnace air can circulate inside cabinets?Also check RV Furnace discharge plenum....might be a 'space' opening to add another duct. Route it to area where plumbing lines run (next to outside wall)?Stationary........skirting around outside of trailer with a 100W light bulb or two under trailer.

All those heating elements would likely require more current so you may have to step up to a site with 50 amp service.We use heat trace at work but smaller heat tape should work for piping. Just make sure to put insulation around it so the heat is held in. You'll likely have to have a controller to turn the heat trace/tape on and off by temperature. We used separate Thermal couples at work. Don't know how residential is but Thermal couples placed at different areas on the piping will help the controller turn the heat trace on and off as needed. The control may even be able to control different zones.Tanks can use heat pads but will need insulation as well. People who live in mobile home trailers do this every year for their piping.Also if you are using 120VAC, you'll need to be permanent. Don't know if a 12V system would provide enough wattage.Good luck.

I would think about installing about a 1 inch thick foam board. Attach it to under belly with screws so as to be able to remove it. The think underbelly cloth does not offer much insulating value.

Heres a kinda of solution that has worked for us and a few others. Very dependant on your situation in regards to where the heat has to go. We needed to insure some heat in raceways where water lines ran in fairly isolated parts of the coach where although they were heated by the furnace they were marginal when it got down to minus 20 etc. I fisched incandescent rope light through these raceways and areas. Heat tape is 18 watts per foot, much more than I needed or wanted. Not to mention, heat tape should be attached to something like a pipe etc. Incandescent rope light is 6 watts per foot, gets warm, not hot and is easy to fisch. Essentially, every 10 feet is like a 60 watt bulb. This approach worked for our concerns. Maybe it would work for you. Good luck. PS, don't get the LED rope lite as it is only 2 watts per foot or less.

Back in the 80s we bought a new full size van and got foam insulation sprayed on the interior walls and ceiling and also underneath. It stayed on and was an excellent insulator. I see it used now for insulating buildings. Apparently it makes them much stronger, too.

Supplemental heat to "basement" | Good Sam Community

Huntindog
Explorer
Sep 20, 2015
ktmrfs wrote:
drill a 1/2" dia hole in the side of one of the floor vents that is in the underbelly. that will direct enough heat to the underbelly to keep it warm. I did this on our outback, put a thermocouple in the belly to monitor, and the underbelly now stays about 10 degrees cooler than the trailer. plenty warm enough. Pick a floor vent near where you are having trouble and drill on the side that will put the air near were you want it.
I have done this, but I went about 2".

Be very sure just what is on the other side befor drilling. You could drill into a tank or an electrical wire etc.
ktmrfs
Explorer II
Sep 20, 2015
drill a 1/2" dia hole in the side of one of the floor vents that is in the underbelly. that will direct enough heat to the underbelly to keep it warm. I did this on our outback, put a thermocouple in the belly to monitor, and the underbelly now stays about 10 degrees cooler than the trailer. plenty warm enough. Pick a floor vent near where you are having trouble and drill on the side that will put the air near were you want it.
Johno02
Explorer
Sep 20, 2015
We used a Clamp-on work light to keep the reflector and bulb from touching anything.
ab257
Explorer
Sep 19, 2015
Put in a light socket away from anything in the basement and screw in a 60 watt radiant terrarium heater?. With a wire cage around it.
Johno02
Explorer
Sep 19, 2015
Used 60W bulbs, has anyone noticed how hard it is getting to find these now?? CFLs won't work for the purpose!
Huntindog
Explorer
Sep 19, 2015
jholovacs wrote:
I fulltime RV, and in the winter, if the temp outside gets below 15F, my kitchen sink lines freeze, even with the heated, enclosed underbelly.

Does anyone know a good product or method for adding a bit more heat to the underbelly that I can wire in in a more or less permanent way? I'd like to flip a switch on cold days and not worry about the matter any more.

I have a spare 110V circuit since I switched to a tankless water heater, so I am perfectly ok with electric, but it needs to be safe, since it's not something I'm going to be able to monitor easily.

Thanks!
Here is a link to what I did.

Heating upgrades
pianotuna
Nomad III
Sep 19, 2015
Nice find!

Pangaea Ron wrote:
I use one of these with a 35F thermo switch in my wet bay to provide additional heat in freezing weather.

Heated Floor Mat
Pangaea_Ron
Explorer
Sep 19, 2015
I use one of these with a 35F thermo switch in my wet bay to provide additional heat in freezing weather.

Heated Floor Mat
pianotuna
Nomad III
Sep 19, 2015
Hi,

I had a similar problem in my Class C. The heater for the cab would prevent the furnace from cycling leading to freeze up of the fresh water lines.

I tried putting a 1500 watt heater in cabinet and running it via my inverter. That did not solve the problem.

What did was replacing the cold air return grill for the furnace with a dual window fan unit. I have it thermostatically controlled with a mechanical thermostat which I place beside the water lines. The warm cabin air blows through and keeps freeze ups from happening.

As an added bonus some air circulates through the furnace duct work.

Do stay away from 'computerized' thermostats and fans. If the power goes off for a second or so, they will default to a power off situation.

If there is an outdoor shower, insulate that area, or do as I did and remove it--then insulate.
Harvey51
Explorer
Sep 19, 2015
Back in the 80s we bought a new full size van and got foam insulation sprayed on the interior walls and ceiling and also underneath. It stayed on and was an excellent insulator. I see it used now for insulating buildings. Apparently it makes them much stronger, too.