Insulating an Imagine for Hard Winter Use.... Big project for me!

[Dadeo6472]

Last year when temps got down to 15 degrees (ski trip) the pipes to the kitchen sink in our 18RBE Imagine froze each night. I said never again and began a huge spring project.

I removed the corro-plast underneath the trailer. I threw away the old corro-plast and the reflective Mylar sheet, which was a complete mess. I added heat wiring and insulated the pipes. I replaced the two inch heat duct to the underbelly with a sealed three inch duct and made a cold air return from the underbelly in the back of the trailer. I sprayed the inside of the steel beams with about two inches of insulating foam (what a mess!). I glued an inch of reflective foam insulation to 6 new corro-plast panels. Once I installed the new, now insulated panels of corroplast, I sealed the gaps around things like drains and pipes (where things went thru the corroplast) and between the steel beams and the new corroplast panels with more spray foam. I sealed the seams between each panel with several layers of heavy duty vinyl corroplast pipe tape. Then we took off on a 6000 mile summer trip across the country and back. I had been worried that the tape between the 6 panels of corroplast might not hold in heavy rain and wind, but it did.

On our trip we immediately noticed that the air conditioner didn't have to stay on as long to maintain a comfortable temps in extremely hot weather. Once we got back I parked the trailer in the driveway waiting for cold weather, leaving the fresh water tank full and the inside thermostat at 50 degrees. When outside temps went down to 10 degrees for days in a row none of the pipes froze. Added bonus, the trailer is using much less propane to stay at 70 degrees.

It was a two week long project, about 6-10 hours a day, but it cost less than $500 in materials. The most expensive part of the project was the new corroplast and heated wiring for the pipes. I also destroyed two pairs of jeans and several cheap long sleeve cotton shirts because of the foam. If I had to do this again I'd get a couple of cheap Tyvek bunny suits to keep the foam off me.

 

[BeerBrewer-MGRV]

I've thinking about doing something similar......Did you take pictures? If so, could you post a few?

Thanks

Bob

 

[Soundsailor]

Great post [MENTION=29635]Dadeo6472[/MENTION], thanks for sharing. This post may inspire others. For me, the question arises: why aren't coaches made this way to begin with?

 

[Second Chance]

Great post [MENTION=29635]... For me, the question arises: why aren't coaches made this way to begin with?

Es obvio... $$$.

Rob

 

[Dadeo6472]

Because it would increase the price or decrease profit. And frankly how many customers really care about using it in winter?

 

[Walaby]

Nice added bonus that A/C's maintained temp easier in hot weather.

Makes me think this might be a project for more than just those worried about freezing weather.

Thanks for sharing

Mike

 

[Dadeo6472]

I've thinking about doing something similar......Did you take pictures? If so, could you post a few?

Thanks

Bob

Sorry, taking pictures weren't helpful in taking things apart, so I only took a couple of fittings at the start. (more on this below)

I can offer some additional details to anyone thinking about this:

Tools needed
portable hammer drill,
a couple of drill bits made for high strength steel, and drilling oil.
wrench bits for the drill to remove and reinstall hex head screws holding the corroplast to the frame.
small wrenches for the tougher to get at screws (mine had hex bolt type heads).
Bit driver with smaller hex wrenches.
Junk screw driver or thin metal bar to help align holes in the corroplast with pre-drilled holes in frame.
full body Bunny suit when spraying foam
furniture padding and drop cloths to prevent driveway mess.
protective eyeware b/c all sorts of crap falls on your face.

Materials: Plastic reflective foam insulalation. Smartshield, From Amazon.
StayPut 2 Adhesive spray for gluing the Smartshield to the corroplast. From Amazon
AgriDrain Amazing Tape 4 inch by 108 ft, From Amazon
70 screws to hold the corroplast to the trailer frame (From Grand Design: ITEM #961041 "SCREW 14 X 1 HEX W/WASHER T-3 SELF DRILLING ZINC $0.36 ea
Heat wires for pipes, enough for all the pipes: 25 feet, thermostatically controlled. It turns on at just above freezing. Available at any big box home store.
3 inch flexible duct -- about 2 feet and elbows
"Good Stuff" spray foam in a spray can.... about a dozen cans.
As cheap as you can find flat black spray paint to coat the foam. A couple of cans.
8 panels of 5mm (1000gm) Corrugated Plastic Sheets (48”x96”x5mm) (special ordered from Cool Seal USA in Ohio, factory direct shipping). This stuff was not easy to find. https://coolseal-usa.myshopify.com/


I thought I could reuse the existing corroplast but found that adding just an inch of insulation below the tanks added thickness, and made the original corroplast bow down just enough to be too short. Set aside at least a couple of weeks and take your time, especially when fitting and cutting the new corroplast.

Take care while removing he old corroplast, you need to use the old corroplast as a pattern for the new panels. Allow for an additional couple of inches of side to side length on the new panels. And you will need to allow for trimming to fit once the panels are attached to the trailer frame.

Make sure the corroplast fits as tight as possible to the trailer, with the least amount of bowing (up or down) in the center as possible. Mark where you removed all fittings (gas lines, hoses, etc) on the trailer. Even if you take pictures, (as I started to) you lose track of where the pictures were taken and the pictures all start to look alike. Instead, mark up the trailer and old corroplast panels as you remove fittings, because you need a pattern to make cutouts for the new corroplast.

Make sure you have a large area where you can lay the old corroplast panel flat. I placed the new panels (temporarily taped together) under the old panels and cut the new panels using the old one on top as a pattern. Follow the old panel cutouts for fittings as much as possible.

Measure three times, cut once. Using the NEW screws, install each of the new panels one at a time, double and triple checking alignment before you screw it onto the frame. I did not overlap panels. Order more panels than you think you will need and more screws than you think you need. I ordered two extra panels, each is 4 feet wide. You are going to make a mistake somewhere. I had to discard the first panel I cut for where the springs and wheels are mounted.

Don't be afraid to cut a few panels narrow to help make it easier to get around the wheels, jacks, gas, water and tank fittings. Its quite a maze under there. It also helps if you have light weight jacks and wood clamps (and a helper) to hold the panels up to the frame while you are aligning, screwing them to the frame and doing final cuts. Throw away the screws you removed when you removed the old corroplast. Many of them will break anyway and you will have to drill them out

After you remove all the corroplast and before you start insulating, spend at least a day and closely examine what remains. Fix fix all original manufacturer workmanship "issues". I found wires and plumbing that went thru roughly cut holes in the frame that were chafed and pinched. Most of the wiring was unsupported. Some of it was pinched between the top of the tanks and the floor of the trailer.

Use wire ties, plastic clamps and the spray foam to secure all wiring and plumbing up and out of your way. Note: I found that the water pressure was better when I was done because a pipe was pinched.

Raise and secure all plumbing as close to the floor of the trailer (off the corroplast underbelly floor) to help keep them from freezing.

I ran the heated wiring inside foam pipe tubes, used one of the AC outlets in the front storage compartment as the AC power source. The pipes are heated only when hooked up to AC power or a generator and are thermostatically controlled to turn on just above freezing. I mounted the thermostat inside the underbelly, so the heating wires would go off when the furnace warmed up the underbelly.

I could find no 12 volt pipe heat tape or wiring

I used the spray glue to make the insulation stick to each corroplast panels before I mounted the panels to the frame. Before installing the corroplast panels, spray the inside of the frame with the insulating foam, be careful that you don't block warm air flow from the furnace duct (to and around the tanks and pipes). You will need to wait 24 hours for the foam to completely set before you trim the foam (remember this stuff expands).

You want the heated air from the furnace to be able to circulate. I had to use a 3 inch hole saw to make a bigger hole for a larger 3 inch duct.

Once the corroplast is installed, use more spray foam to seal all gaps around all the various fittings underneath and the remaining gaps between the corroplast and the steel frame. Use the vinyl tape to seal cracks between each corroplast panel. Buy extra tape so you can use it for future repairs. Its pretty easy to work with and don't worry about how smooth it goes on, just add more layers as needed to ensure a good seal. Use more, not less.

To ensure maximum circulation of warm air in the under belly you need a return air vent back into the trailer to the furnace. Ideally, the warm air duct from the furnace and the return air vent are be spaced far apart so the warm air moves from the furnace down and around the pipes and tanks.

In mine, the hot air duct drops down from the furnace near the fresh water tank and fresh water pipes, then the warm air circulates around the gray and black tanks before recirculating back into the trailer as cool air at the back of the trailer under the shower, where I found a good sized plumbing air gap. I just had to drill a dozen one inch holes in the plastic access panel that is under the front of the shower so the air could circulate.

I sealed the gap around the warm air duct into the underbelly with more spray foam. There is no purpose in sending warm air down there if it just comes rises back up around the duct

Other thoughts..

Why doesn't the manufacturer do this to begin with? My guess is they don't do it for the same reasons that overall workmanship in the RV industry is so poor: it would increase price and cut profits. And why bother when you can't keep up with demand now? Most buyers only use their camper in warm months so they don't care. Also, unlike manufactured housing (AKA mobile homes), these things are not regulated for energy efficiency by local or state codes or the federal government.

 

[FT4NOW]

Good job and write up. They do make 12v heat tape, probably similar to the tank heaters on the 5th wheels, they are all 12v and have built in thermostats. Unless you're going to be dry camping in freezing temps, nothing wrong with using the 120v heat tape.