mavapa
Rome, Ga, USA
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Joined: 11/08/2002
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I have tried searching for this because I thought I remembered someone talking about it, but I can't find it. The question is, what's the best way (or any way) to insulate holding tanks that are exposed on the bottom of a Class C? The gray and black tanks have 12V heating pads, but I want to avoid their use if possible. Has anyone done this, and if so, what did you use?
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Polishnurse
Schodack, NY
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Joined: 03/13/2007
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Insulating the tanks will not keep your tanks from freezing, it will lower the amount of heat needed to keep them from freezing. If this is your goal, I would think that just purchasing some of that pink foam board from Home Depot or Lowes would be sufficient for most cases, then use some PL-200 or other construction adhesive that can be used to for the application of foam board.
You can just glue it to the sides of the tanks making sure the outside edges have a bead. Since it would be applied more like a jacket, a few spot left uncovered won't be that critical in the overall project.
I would recommend that you use 110 self activating heat trace similar to this one. There are several different manufacturers but will have to be ordered form an electrical supply house. I would be sure to do the waste tank drain pipes in valves since these are prone to freezing also. I have found the valves to freeze before the rest of the system.
I have also wrapped my waste pipes with fiberglass insulation, then used a plastic wrap, then black duct tape. to keep moisture of loading the insulation.
This application would be good for an unclosed system (open under belly).
The self activation heat trace will never get to hot, like the cheaper Walmart or Depot types, that specify not to over lay the wire when wrapping. They have been know to catch fire from the heat they can produce. The self activating heat trace likes to be 40 or 50 degrees, if it gets warmer, it shuts it self down for that area of the tape. The rest of the tape will continue to produce heat and regulate it's self.
Good Luck and happy heating Bill .
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mavapa
Rome, Ga, USA
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Joined: 11/08/2002
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I'll only need to worry for three nights a week, and we have very low temperatures only infrequently and not for long, so a little insulation will probably solve the problem. I won't have access to AC during those nights. I wonder how flexible construction adhesive is.
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Polishnurse
Schodack, NY
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I think you find construction adhesive will harden up of the years and become brittle. You can try a silicone adhesive, and also a strapping.
The foam board is relatively cheap, you could try making a box out of it that can be dropped and removed. Perhaps stored inside when not needed, The hole assembly would weigh under ten pounds. Bill
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pinesman
virginia
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Joined: 08/21/2006
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Something I did was to wind a heat tape around all the drain pipes. It is lower than the tank and the heat will rise. I have never had to rely on it in extremely cold temperatures and it has always warmed up during the day but so far so good.
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goff1256
co
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Joined: 11/01/2008
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Find a spray fome insalation company to spray it for you .
Erick & Jackie Goff; Plus Sophie the Fu Fu Dog
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double jj
bc
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Joined: 10/26/2009
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If you feel like going all out. Build a box around the tanks and direct a furnace duct into that area but make sure it's circulating. This is a big job.
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T_Bone
Arizona
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Joined: 09/20/2001
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Hi Mark,
The 2" rigid styrofoam at HD and such is the best bang for the buck.
Closed cell pipe insulation for piping.
Both are in the R6/7 class where all other insulation is in the R3/4 per inch class.
You will also need to skin the bottom with plastic or thinn sheet metal too stop air flow into and out of the insulation no matter what type of insulation that you use.
A perfect vacuum is equal too R270. That's not a typo, R270 
T_Bone
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Please do not trust everything you read on the internet. Use only valid engineering information from well established Companys.
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mavapa
Rome, Ga, USA
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Joined: 11/08/2002
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Thanks for the replies. I might try to use some silicone sealer/glue to attach some sheets of foam insulation. I might not get complete coverage, but, as I said, the conditions here are not really extreme. I have only had my tanks freeze once in the last few years. The cold snap lasted about three days and then everything thawed.
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WILDEBILL308
FORT WORTH , TEXAS
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Joined: 12/07/2003
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Try pre fitting your pices then using spray on foam to glue the parts on the tank. You woulden't believe how well it stickes. Just get some on you and you will believe.
Bill
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