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Old 11-14-2013, 11:22 AM   #15
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Good points. Worst case scenario, as longer as the tanks aren't completely full, what's the worst that would happen? Frozen dump valve? I suppose the tank itself isn't likely to crack unless it is completely full....
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Old 11-14-2013, 11:26 AM   #16
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I suppose the tank itself isn't likely to crack unless it is completely full....
Half full is best for that. Assuming that the tank walls are straight up and down, then at half full they have the most flex if they do bulge from ice expansion, and are less likely to crack at a seam.
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Old 11-14-2013, 11:26 AM   #17
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A quick google search and it appears water typically expands 9%. That's not much, so I suppose unless a tank is full, the likelihood of real problems is minimal.
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Old 11-14-2013, 11:30 AM   #18
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With a 25 gallon tank, at half full at 12.5 gallons it might expand 1.125 gallons. That's not much--why would even 80% full be an issue when there would be plenty of room along the top of the tank for expansion?
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Old 11-14-2013, 11:34 AM   #19
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With a 25 gallon tank, at half full at 12.5 gallons it might expand 1.125 gallons. That's not much--why would even 80% full be an issue when there would be plenty of room along the top half of the tank for expansion?
Ice doesn't just expand up; it expands out to the sides, too.
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Old 11-14-2013, 12:17 PM   #20
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A quick google search and it appears water typically expands 9%. That's not much, so I suppose unless a tank is full, the likelihood of real problems is minimal.
You also have water in the pipes and fittings which will crack very easily under freezing conditions. I have had to replace more than my fair share of silcocks that have frozen in relatively mild conditions because they were either not drained or covered.

If your trailer still has the duct work from the original furnace still in it, I don't see why you couldn't add a small duct with a fan to carry heat from a near by ceramic heater into the tank area, bound to be cheaper than the tank pads, or having to replace a tank or fittings due to freezing.

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Old 11-14-2013, 12:33 PM   #21
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I don't think the tanks would be damaged by water freezing in the tanks unless they are close to full. Ice will move in the direction that it can just like in an ice cube tray. It does not freeze instantly and all of a sudden increase in all dimensions by 9%. You might have problems with valves especially if you have a leaker and the space between the valve and the drain cap gets filled with water. This would also allow the valve body to fill with ice and potentially crack that as well. So I would remove that outside cap or remove the hose connector like mine has. You could put a thermocouple on the ground terminal for the tank sensors. When that got to 32F or below then you need to worry.

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Old 11-14-2013, 12:49 PM   #22
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Just freeze a milk jug for ACCURATE observation of how water expands when frozen. Do it half full, 1/4 full, and filled full. Draw your own conclusions from you very own observations.
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Old 11-14-2013, 01:44 PM   #23
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Just freeze a milk jug for ACCURATE observation of how water expands when frozen. Do it half full, 1/4 full, and filled full. Draw your own conclusions from you very own observations.
Yeah. The damning thing about water is that it doesn't freeze all at once - it freezes outside in. So the top level of the water will freeze first and probably not cause a single problem, but then the layer underneath will be enclosed and put more pressure on the sides of the tank, and so on... Sure, there might be enough room for all of the ice above the level of water in the tank, but the ice won't be able to use that space.
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Old 11-14-2013, 02:11 PM   #24
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Here's how I cheapened out. We lived in our MH in 1 spot for almost 3 years. Before winter came, I would buy a 20' heat tape meant for pipes. I would put about 7 feet in a Z pattern under the grey tank on a piece of regular house insulation. I would hold this up to the bottom of tank with one of those small fish nets used to hold a helmet on a motorcycle. Wrap the drain from the tank to and around the dump valve. Continue back up the Y in the pipe to the black tank. Be sure to get the black tank dump valve too. This would use about 6 feet. repeat the process for the black tank. This didn't look pretty but it worked. The heat tape was on at all times. Of course I would have to remove it when driving, then reinstall. This was easy as MH's tanks aren't behind belly wraps. Maybe with the wraps, you can leave it permanent on a TT.
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Old 11-14-2013, 03:32 PM   #25
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I am building my own tanks out of black 1/4" ABS that has been tacked with Weldon, then heat welded, then solvent welded on top of that inside and out. I planned on using prodex insulation to wrap the tanks except where they touched the underside of the floor.

My tanks are all sloped on the bottom, and very slick inside, so I'm hoping that will help with some issues.

However, I am considering the tank heater option by using 3M adhesive to glue a waterbed heater to the bottom of my tanks, then using the prodex to wrap the outside of the tank heater, then using straps outside that.

I plan on then running the cords up to the inside of the trailer, and tying them in somehow to a single switch. Then, the belly pan goes outside that. I may strap directly to the tank, then use a softer strap to hold on the insulation to keep from having the straps wear through the heating pad.

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Old 11-14-2013, 08:40 PM   #26
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Interesting idea. I found this one that's 300 watts and costs $71 on Amazon.com. I don't see why it wouldn't work; just need to adhere it to the bottom of the tank.
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Old 11-14-2013, 09:27 PM   #27
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So, if I pour a bottle of "crystal clear" into the fresh water tank will that stop me from worrying about it freezing?

Will it drop/ lower the freeze point to say 20 degrees? That would cover most weather here in Central Texas. And, I will have a good start for any drinks....

Just kidding, sorta. Guess drain or pain?

I left the furnace on overnight when we hit freezing. In the morning, I checked the water temp... Very cold... But I neglected to check actual temp. ... Minus the alcohol additive.

Anyway, I wonder if AS has done environmental chamber readying of "freezing" results on the AS design?
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Old 07-17-2017, 03:54 PM   #28
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Update

An update on the four years old post would be super timely for my own renovation. How did your installation work? I am interested in the 1) insulation with prodex - does it make a difference; 2) heating pads - are they really a solution?

I need to order two grey water tanks and the size will depend on whether I insulate them or not. I am considering prodex but also, the plain pink closed cell foam.

One quick question... If you were to link the two grey tank together to enlarge the overall grey water capacity, would you put the pipe at the top or the bottom of the side tank? Bottom seems most logical to me but given the discussion about freezing pipes, I am wondering if higher up may be better.

Thanks for your advices.

Julie
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