Fresh Water Tank Freezing

Thanks for the replies.

I know that everything will eventually freeze and I know my question has too many variable for a correct answer. I figured (maybe incorrectly) that if I knew how long it might take a 30 gallon container to freeze up (no insulation, no heat added etc) that I would have a benchmark on when I should get seriously concerned about applying heat or dumping water.

Drain pipe valve and the small pipe running from the tank to the pump are something that need attention. Insulating those might bring them back into line with my original question which boils down to something like .... if it got down to 32 degrees in PDX how long would it take a 30 gallon RV water tank to freeze (assuming the RV interior temp was 32).

Thanks.

ksg5000 wrote:
if it got down to 32 degrees in PDX how long would it take a 30 gallon RV water tank to freeze (assuming the RV interior temp was 32).

Never. Well, ok, a long, long time.

They do make external tank heaters, ones that stick on the bottom of the tank. I don't have any experience with them, but knoe they are available.

I do agree with others about the issue with rigid fittings an pumps being vulnerable.

Has anyone tried to set up a warm water circulation system, using the HWT set at the lowest setting?

If you really want to do battle with freezing weather... stick on pad for the tank and aluminum foil + heat trace for the plumbing. or get an oil filled electric heater, and leave it set at 55-60F.

you'll need to identify your plumbing weaknesses. my KZ for example has the majority of the plumbing inside the heated insulated area, except for the main line from the pump, and the cold water feed to the hot water heater. The main line I wrapped with aluminum and then heat trace. The water heater line I can't get at, it's behind the black tank which I'm not dropping. It's good well below 0F, but does become "slow" around -15F. Those temperatures aren't likely in PDX.

WNYBob wrote:

Has anyone tried to set up a warm water circulation system, using the HWT set at the lowest setting?

Yes, I built one for my trailer. It's controlled by timer and thermostat, and works very well in very cold temperatures.

Depending on outside temp, it runs every 10 minutes to every hour. Once it is circulating, it continues until the cold water line temp reaches 40C. A tiny pump installed under the kitchen sink, check valve and a shark bite ball valve keep things moving in the right direction.

If you want a "lifeboat" I'd have like 10 gallons (2 five gallon jerry cans) of water inside the sticks and bricks and if you need to book, take 'em out to the RV and re-winterize by the "S" method (Drive soUTH) till you can tank up. Use the jerry cans inside till you get warmer.

We live in northern Alberta at the same latitude as Dawson Creek, mile zero of the Alaska Highway.

We experienced some freezing in our first RV trip when temps dropped to -10 C, 15 F in a March blizzard. We stopped at a roadside campsite with no services because driving was hazardous in the snow and enjoyed our new house. I was worried about the water lines and kept checking the freshwater drain. That tap is several inches out from the tank and it did freeze. I put a mitt over it and went to bed with the furnace set to keep the house at 60 F. In the morning the tap was not frozen and allowed water to flow out. No problems with the water in the house, either. We were lucky to learn so quickly that our MH can handle -10 C. We have avoided camping in lower temperatures and carry a gallon of RV antifreeze in case of chilly surprises. Only one other problem - a drain pipe elbow under the floor cracked, possibly due to freezing.

I am familiar with other affects of freezing water. Notably when a steel barrel of water, open at the top, freezes, it pushes out the bottom to form a dome shape. I have several rain barrels that have that problem. It suggests that damage would occur to a half full freshwater tank that freezes. It would, of course, freeze more quickly than a full tank because of the larger latent heat of fusion of the larger mass of water.

wa8yxm wrote:
If you want a "lifeboat" I'd have like 10 gallons (2 five gallon jerry cans) of water inside the sticks and bricks and if you need to book, take 'em out to the RV and re-winterize by the "S" method (Drive soUTH) till you can tank up. Use the jerry cans inside till you get warmer.

This is the simplest way to have water when it's cold out.

You can install a heat pad with a thermostatically controlled connector to power. If you insulate outside of the heat pad and tank with extruded foam board, you won't use a lot of power in Oregon to keep the tank liquid. Installing an additional heat tape around the tank output and the pump might save your bacon, too.

FWIW, years ago, I built an enclosure around an above-ground pipe array in St. Paul, MN. The pipe array and manifold needed to be operable through the Winter. I made a plywood box with removable cover, insulated with 2" extruded foam, and installed a 100W light bulb with fixture. At -10f, the temperature inside the 4' x 8' enclosure was 80f.

To get an estimate you need:
- Starting Water Temp.
- Insulating factor
- Wind conditions
- Air Temperature Profile.

The last is absolutely critical.
- If early morning it gets down to 30F after a calm night, you might get a light skin of ice at the top...if that.
- If it gets down to -10F with a strong wind, good chance, you have a 50gal block of ice in the morning.

2oldman wrote:
Every google search I find says there are too many variables to even make a guess. We don't know the tank's exposure, the mean 24hr temperature..etc.

Since you're in OR I would guess it would never freeze. In Fairbanks AK, yeah, it would. I assume you are draining the lines, which are obviously in more danger than a tank.

We are in Oregon and last winter there were quite a few campers who had their fresh water tank freeze.