Tank heaters and insulation

Tips and tricks for cold weather use of your Avion
KYAvion
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Tank heaters and insulation

Post by KYAvion » Tue Dec 19, 2017 10:35 pm

Since I do a lot of winter camping, I've decided to install 12v heating pads on the black tank and the pipe between the tank and gate valve. I installed a 12" x 18" pad on the black tank and a 7" x 25" pad around the pipe exiting the black tank. I installed both and unfortunately the 12" x 18" pad doesn't work. I've ordered a replacement, but decided to go with two 7" x 25" pads on the black tank so if one happens to fail the other will still do the job. Since I leave my trailer plugged in 24/7 and it takes awhile for the black tank to fill up, these pads will allow me to use water in the toilet as opposed to flushing with antifreeze as I've done in the past.

So while I had the underbelly taken apart to install the pads, I removed the nasty fiberglass insulation. In the meantime I'll put new fiberglass back in place, but I wondered why Avion didn't apply spray foam to the outside of the tanks? Off the top of my head, I can't think of any drawbacks. The foam would make isolating a leak more difficult, but generally that's not a concern.
KYAvion
1984 Avion 30R

silverloaf
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Re: Tank heaters and insulation

Post by silverloaf » Thu Dec 21, 2017 11:10 pm

I decided not to replace the fiberglass insulation below the black tank. When I dropped the belly pan in August, the insulation was saturated with water. The sub-cross members adjacent to the dump valves were rusted out.

I believe a leaky toilet flange and condensation of the steel around the tank were the primary sources for wetting the insulation. I noticed droplets of condensation on freshly-painted steel cross-members as I installed new belly pan.

A few days later, I removed a few screws around the dump valve. I was greeted with a puddle of water dripping from the pan. I installed some 4' x 16" air vents in the belly pan to reduce the humidity above the pan.

I agree with you that Avion should have sprayed the tank cavity with foam. Have you thought about installing a sheet of 1/2" foam board below the tank? Mine had about 1" clearance to the tank and pan.

Bob

KYAvion
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Re: Tank heaters and insulation

Post by KYAvion » Fri Dec 22, 2017 8:44 am

I thought about foam board as well. I've used a lot of that stuff at home and it works great. For the tanks I think the foam board would work best if pieces covered the sides as well, and joints sealed with a can of spray foam so the sides and bottom of the tank are sealed and enclosed. Not that it's really needed with a tank heater, but I didn't se an obvious path for air from the furnace. I imagine the supply duct is at the freshwater tank.
KYAvion
1984 Avion 30R

silverloaf
Posts: 102
Joined: Wed Aug 23, 2017 8:01 pm

Re: Tank heaters and insulation

Post by silverloaf » Fri Dec 22, 2017 10:27 am

I do have a small duct from the furnace to the freshwater tank cavity. It's weird the remaining tanks have no heat source.

Insulation alone will not work. At some point, the cavity and the tanks become the same temperature. It merely turns the cavity into one big freezer and takes forever to thaw out.

(PS: I used to do building performance diagnostics and insulation work).

The vents I installed in the belly pan are for ambient air exchange only. Any humidity or condensation trapped between the floor and pan will eventually dry out. The down side: winter camping is not an option right now.

Yes, fully encapsulating the tank cavity with spray foam or foam board might be ideal. But clearance constraints around the tank might make it unfeasible.

I have a question on winter camping. How effective is your water heater to raise the temperature of colder water?

Also, what's the coldest temperature you have encountered and still remained functional?

Bob

KYAvion
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Re: Tank heaters and insulation

Post by KYAvion » Sat Dec 23, 2017 9:21 am

My primary reason for insulating the black tank is to reduce heat loss from the tank heaters, and thus hopefully decrease their run time some. As far as the other tanks and insulation, I would think there'd be some degree of residual heat (not counting the furnace duct) from inside the trailer. I get what your saying about things becoming a freezer, but while the trailer is in use it seems insulation along the bottom (and maybe sides) would help. I actually have quite a bit of space below my black tank. For now I just ran fiberglass for 2x4 walls, but later will cut a fit a sheet of foam.

As far as camping in cold temps, I have camped down into the teens near single digits and been fine. A heavy wool blanket or electric blanket is nice to reduce furnace run time. In terms of the water heater, the number of minutes of available hot water certainly does decrease. I have a shut off on the shower head that really helps to conserve hot water while showering. A 10 or 12 gallon water heater would be nice, or even a second 6 gallon (which I'm considering), but for now using the shut off does the trick. An instant water heater would be the best, but I like the simplicity of the tank units. Even the direct spark with all the features is easily fixable if one has the parts on hand.
KYAvion
1984 Avion 30R

silverloaf
Posts: 102
Joined: Wed Aug 23, 2017 8:01 pm

Re: Tank heaters and insulation

Post by silverloaf » Sat Dec 23, 2017 1:32 pm

My wife came across a picture of a travel trailer on Pinterest some time ago. Someone had made a detachable fabric skirting that extended from the trailer wall to the ground. The skirting was high enough at the front to cover the LPG tanks.

Have you ever seen that done by cold weather campers? I suppose the trailer could have been used as permanent living quarters.

Bob

nralifer
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Re: Tank heaters and insulation

Post by nralifer » Sat Dec 23, 2017 3:20 pm

I had given some thought to some skirts like that if we were to do more cold-weather camping.

First, I would lay down some thick plastic sheeting under the Avion as a barrier, snap the skirting onto the lower edge of the Avion (like the "tropical rooms" are done), and I would opt for some tent stakes to keep it from blowing in the breeze. I would probably get some fabric from Zip-Dee to match the awnings, or, I might contact Alaska Tent & Tarp (where I have gotten front grill covers for our F250 and Bronco) and see if they could provide some material based on measurements I'd give them. http://alaskatent.com/covers/grillcovers.html

Then, with that sealed, you could even run a small electric heater under there, assuming you had a 110V connection.

Here are some pictures of a skirt on a basement model:
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nra1ifer
1987 Avion 34W
Every day is a good day..... some are just better than others!

silverloaf
Posts: 102
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Re: Tank heaters and insulation

Post by silverloaf » Sat Dec 23, 2017 9:02 pm

I would think the skirting and small 110v heater would keep the tanks and plumbing from freezing.

Of course, boon docking would require a small generator to power the heater.

Nevertheless, it looks like a good plan.

Thanks for the pics.

Bob

KYAvion
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Re: Tank heaters and insulation

Post by KYAvion » Sat Dec 23, 2017 11:55 pm

I've thought about the skirting to help keep the floors and interior warmer, but from what I can tell it's pretty pricey. As far as the tanks, I've never had an issue with them as long as I'm IN the camper using it. I only installed the tank heaters on my black tank to keep the tanks from freezing between uses of my trailer. If I only used the trailer occasionally throughout the winter I probably wouldn't have messed with them and would have stuck with flushing with RV antifreeze instead. That said, the tank heaters are a relatively simple install.
KYAvion
1984 Avion 30R

KYAvion
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Posts: 476
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Re: Tank heaters and insulation

Post by KYAvion » Sat Dec 23, 2017 11:59 pm

Before going with skirting I think I'd go with storm windows to help with the heat loss through the single pane glass. Anyone see an Avion with factory ones before?
KYAvion
1984 Avion 30R

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