Exterior foam insulation on black tank

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Exterior foam insulation on black tank

November 07, 2019, 05:01:35 pm

Hi all:

I have a 31 foot LD we purchased new. We had the holding tanks sprayed with foam for cold climates I had to remove some of foam but having difficulty getting the new spray

foam to hold, -it falls away when sprayed on. I had some success but need some suggestion on how to have it stay up there.

Thanks

Bob

Re: Exterior foam insulation on black tank

Reply #1 – November 07, 2019, 05:38:34 pm

Hi Bob. In my experience using foam from a can; smear a small amount using a rag, or glove to get that to stick on the tank. Then you can spray more on top of that. It always seems to stick best to the things you don't want it to. I think the first amount out of the can, the surface dries almost instantly, so it doesn't really stick so well. The tank area must be clean and dry, but a quick wipe with acetone just before you start spraying (a few seconds! before) would help I think. RonB

Re: Exterior foam insulation on black tank

Reply #2 – November 07, 2019, 06:29:23 pm

I wouldn’t worry about it. If you’re in really cold weather, the tanks will eventually freeze anyway and the insulation will just make it take longer to thaw. If it’s not really really cold, you don’t need to keep,the tanks from freezing.

The only advantage I see is that the foam mildly protects the tanks from rocks and things thrown up from the road.

My LD has insulated tanks but I wouldn’t spec them if buying new.

Rich
‘03 MB in NC

Re: Exterior foam insulation on black tank

Reply #3 – November 07, 2019, 06:47:51 pm

"My LD has insulated tanks..."

As do mine! But in 18 years I've never been in weather cold enough to test it. Once in Colorado (near Royal Gorge) and again in Taos where the C.G. Host asked that we disconnect from the water supply. I believe that heat tape wrapped around the dump valve plumbing would be more beneficial.

Re: Exterior foam insulation on black tank

Reply #4 – November 08, 2019, 12:17:37 am

"If you're in really cold weather, the tanks will eventually freeze anyway and the insulation will just make it take longer to thaw."

Rich nailed it. My midbath (purchased used) had foam on the tanks. It was useless or worse than useless for exactly the reasons he mentioned, and it made installing better tank gauges, etc. a royal pain.

Re: Exterior foam insulation on black tank

Reply #5 – November 08, 2019, 08:20:18 am

THANKS FOR YOU INPUT, WILL MOVE ON.

P.S. All the gauges still work, hope they will for the next 10 years.

Bob

Re: Exterior foam insulation on black tank

Reply #6 – November 08, 2019, 12:58:47 pm

[quote ]
I believe that heat tape wrapped around the dump valve plumbing would be more beneficial.

P.S. All the gauges still work, hope they will for the next 10 years.
[/quote]

The holding tank valves and associated plumbing can freeze overnight in cold conditions while it may take the tanks several days to freeze. Installing 120-VAC heat tape to the valves and plumbing with enable draining the unfrozen tanks.
Our valves have frozen several times, powering the heat tape thaws them in about an hour or the power may be left on all the time. I removed the entire holding tank valve manifold and then wrapped it in heating tape and then covered it with a waterproof foam insulating tape. It isn't wire into the LD's electrical system, instead, an extension cord is used to connect directly to power, simplifying the install .
Winterizing holding tanks | Flickr

If you can scrape the foam off the tank, a set a SeeLevel sensors can be attached for use with the remote monitor.
They are more dependable than the stock tank level pins and supply a lot more information.

Larry

Re: Exterior foam insulation on black tank

Reply #7 – November 08, 2019, 04:24:29 pm

We have found that when we have been traveling into freezing conditions we first flush window washer fluid that is freeze resistant into our 98 ~ MB Gray and black systems so the fluid is against the valves to protect from freezing. We use the washer fluid because we get it cheap when it goes on sale for around $1.00 a gallon. RV anti freeze would work as well but cost usually more. This has worked for us when we are going to altitude where it is freezing but later when we descend and dump it is warmer. A couple years ago we stayed at Mamouth Mountain RV park for a week and did a couple dumps at their dump station when it was cold staying below 25 degrees and we did not have any freeze ups, although our dump hose froze in the storage tube and became damaged on the end which we had to cut off, now we have a 8ft dump hose to remind me that things do freeze. My guess is that Larry's solution is a better idea for protecting valves from freezing.

Karen~Liam
98 ~ MB
NinA

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