Putting heater under trailer?

[Bandit12]

I'm going to ask a dumb question here and if anyone thinks I should start a separate thread, please feel free to let me know. We recently moved to SW South Dakota. While it hasn't been bitter cold for long periods yet, it has gotten down to single digits a few nights. We do not yet have skirting around the bottom of the trailer. Our underbelly is enclosed and I know the furnace is ducted into that area. We also have tank heaters and those have been turned off since mid Oct. Nothing has frozen yet. My question is, when I get the skirting in place probably early next week, what's the consensus on placing a small space heater, 1500 watts, set.on low under the trailer? Would be of any benefit or would it be a fire hazard?

[Rhyno]

Originally Posted by Bandit12

I'm going to ask a dumb question here and if anyone thinks I should start a separate thread, please feel free to let me know. We recently moved to SW South Dakota. While it hasn't been bitter cold for long periods yet, it has gotten down to single digits a few nights. We do not yet have skirting around the bottom of the trailer. Our underbelly is enclosed and I know the furnace is ducted into that area. We also have tank heaters and those have been turned off since mid Oct. Nothing has frozen yet. My question is, when I get the skirting in place probably early next week, what's the consensus on placing a small space heater, 1500 watts, set.on low under the trailer? Would be of any benefit or would it be a fire hazard?

It's always a risk putting a heater in a confined space. We have a 400w heater in the front storage compart plugged into a GFI plug. It keeps the storage area and hot water/ furnace area at about 20° Celsius when its below 0 celcius. Problem is there is another bulkhead in front of the tank area. This only gets heat from the furnace.

[Bandit12]

For reference, I am considering placing the space heater on the gravel surface, underneath the trailer, plugged into the power pedestal at our site. While the underbelly will be skirted, it won't be completely sealed .I'm just looking to block the majority of the wind, and possibly adding a little heat underneath the trailer.

[notanlines]

We don’t know where you are or the model of your RV.

[jasin1]

I use this large boat safe heater for my engine room in my boat if i choose to leave in the water over the winter…i have the smaller one for my sons old boat …new one doesn’t need it

don’t know if it would help in a underbelly but the xtreme bilge heater claims you can use it in rvs …they have a built in thermostat and are ignition protected which may be a good idea with propane in close proximity especially with the iffy propane connections (and possible leaks)run thru the trailer

i still don’t think i’d be putting one inside a underbelly though and don’t think it would help much under the trailer with skirting

[Bandit12]

I have a 2021 Cougar 27SABWE, we recently moved to Hot Springs South Dakota. Southern area of the Black Hills.

[Bandit12]

While it hasn't been bitter cold for long periods yet, it has gotten down to single digits a few nights. We do not yet have skirting around the bottom of the trailer. Our underbelly is enclosed and I know the furnace is ducted into that area. We also have tank heaters and those have been turned off since mid Oct. Nothing has frozen yet. I'm planning on skirting the trailer using 2 inch think foam board insulation. The aluminum side skirting on the trailer is about 2 foot off the ground. I don't think the foam board will be tightly sealed all the way around the trailer, I'm simply looking at blocking the majority of the wind.

[JRTJH]

To explain posts # 1 and 2 above, they were initially in a different thread so I moved them to this thread since they were posted by the same member and are the same topic. Hopefully, they will add more information regarding the location and the trailer/circumstances surrounding the topic.

[fjr vfr]

I'm not sure what to advise without seeing up close what you're trying to do. But, in an enclosed space under a trailer I'd be more inclined towards a small oil filled heater like below. I think it would be safer left alone than a fan type heater. You could even use two of them and space them apart for more even heating.

https://www.amazon.com/Air-Choice-Th...232e75a0a&th=1

[flybouy]

I don't think you'll see any effect from a 5k btu heater. A 5k btu heater is 1/6 or less the output of the LP furnace. The furnace can struggle to keep the insulated and somewhat airtight space warm in very cold Temps. A heater on the ground would not help the pipes either as the insulation on the underbelly will block the heat.

[RickV]

I don't know enough about this and I know someone will correct me if I am wrong but, wouldn't the tank heaters help keep things in the enclosed underbelly from freezing?

[JBM3M]

Having been an insulation contractor at one point in life....The foam board will do the most good. Air tight is not possible or even reasonable, you want moisture under there to move on. The first R4 makes the most difference. Looking under the belly of my RV, (it has the polar package) there is a layer or coroplast on the bottom. If I were really concerned about keeping the RV warmer and preventing freezing I would attach a 1" layer of isocyanurate (sp) foam to the bottom of the RV, that should give you additional R8. Then use 1" expanded polystyrene for the skirt (R4). That should prevent any freezing in your climate. Just make sure your pedestal water line is heated. The isocyanurate is much more expensive than the polystyrene, but much better insulation value. This would allow not using a heater under there, the foam is very flammable

[notanlines]

Sorry Bandit, I was reading on my phone and the info didn't come up!

[wiredgeorge]

Originally Posted by jasin1

I use this large boat safe heater for my engine room in my boat if i choose to leave in the water over the winter…i have the smaller one for my sons old boat …new one doesn’t need it

don’t know if it would help in a underbelly but the xtreme bilge heater claims you can use it in rvs …they have a built in thermostat and are ignition protected which may be a good idea with propane in close proximity especially with the iffy propane connections (and possible leaks)run thru the trailer

i still don’t think i’d be putting one inside a underbelly though and don’t think it would help much under the trailer with skirting

Welcome back to the land of the living!

[jasin1]

Originally Posted by wiredgeorge

Welcome back to the land of the living!

I was thinking about starting a thread about tire pressures or china bombs just to stir things up but thought better of it

[flybouy]

Originally Posted by RickV

I don't know enough about this and I know someone will correct me if I am wrong but, wouldn't the tank heaters help keep things in the enclosed underbelly from freezing?

Only the tanks that they are attached to. Tank heaters will do nothing towards preventing the water lines from freezing.

[Richeyb]

I prepared my old 1999 Keystone Sprinter for my granddaughter to live in during the cold winter of Idaho. Added tank heaters, foam board insulation taped to side of trailer and nailed to 2x4s nailed to the ground, and placed two chicken coop heaters under the trailer with a temperature control to come on at 40 degrees. With the addition of a couple small space heaters she survived without using too much propane.

[Bandit12]

I got the trailer surrounded by 2 inch foam board insulation. It is by no means air tight. I used several pet fence panels to hold the boards against the trailer. For the back, i removed my cargo tray, crawled under, had my wife hold the board in place while i marked the receiver hitch location. Cut the hole for it, set the board back in place and reinstalled the cargo rack, sans hitch pin. Seems to be holding it in place fairly well. This morning the winds kicked up to 25-35 with higher gusts. One of the boards disappeared, I later found it underneath the trailer on the opposite side. Wind blew hard enough to push the bottoms in and move the 4x8x18 wood blocks I had placed inside the foam boards. I also had one piece outside the slide out the the wind blew inboard and pinned it against the wheels. My wife helped me get that back in place, I crawled under the slide out and put the wood blocks back in place, but this time I pit the on their edge so they sit higher and fixed them in place with 10 in tent nail pegs. I also placed a 1500 watt ceramic utility heater underneath aimed generally towards to tank drains. We also added so silver HVAC metal tape to secure boards together. I've also ordered additional fence pole stakes and I'm going to try to add more fence panels on the west (slide out) side as it receives the prevailing winds. Talking with the gentleman that owns this place, he looked at what I have and said it should do well, including the heater. Forgot to mention, the heater is thermostatically controlled, has an overheat protection circuit, andvi looped the plug on top of the handle to keep it off the ground.

[dutchmensport]

I don't think adding heat under the trailer, inside a skirting will HURT anything. But, I also don't think it will HELP anything either. Why, the space is too big, to open, and too many air gaps.

The skirting will prevent wind from blowing under the trailer. Any time you can create a wind block, things will feel warmer.

As stated above, the underbelly of the camper is insulated. Any heat from a heater under the trailer will simply be lost (too drafty). The wind block will do more good.

However, if you do end up putting heat under there, then don't use anything with a flame. Use electricity only. Anything with a flame will need to be vented. The last thing you want is carbon monoxide to creep up into the living space of your camper. That only happens with unvented fumes from fire based appliances.

[JRTJH]

Looking at your photos, I have a few observations and suggestions:

1. You installed foam board around your trailer, but failed to extend that foam board up the sides of your slide. What you didn't do was help insulate the rubber seals around the slide opening and add insulation to the 1" slide sides. If I were you, I'd extend the foam boards up along the slide sides, paying attention to getting the foam next to the rubber seals, then secure the foam using tape to help seal any drafts away from the rubber seals. You can cut out the space for the windows if you prefer, but that will reduce the insulation at the single pane window locations. You can also put foam board on the roof of the slide and under the slide if you want. Those locations, like the sides, are minimally insulated and anything you do to improve the r value will help keep you warmer. Also consider that those rubber seals are located on both sides, top and bottom of the slide opening and anything you do to help reduce drafts will keep you warmer.

2. Now, my take (for what it's worth) on heat under the trailer: As air warms, it expands and increases the capacity to hold moisture. Moisture collects (condenses) on cooler surfaces pulling that moisture out of the "warmer air".... What does that mean for you??

By putting a heater under your trailer, you're going to warm some of the air and help that air to pull moisture from the ground under the trailer. That moist air will then condense on the inside of the foam, along the exposed frame rails of your trailer and the J-wrap that is not as well insulated as the underbelly. So, in short, what you'll be doing by putting a heater under your trailer is wasting electricity (it won't keep you warmer) and increasing condensation under your trailer which will reduce the r value of your fiberglass insulation in the underbelly, increase humidity and potentially enhance mold/mildew formation and create a "perfect storm" for rust/corrosion on your undercarriage.

I'd think through the "heater operation" under your trailer. It likely will make things worse rather than better.