How to Heat Water Tank

FreezingMan said:
Like the original person's post I'm looking for ideas to better protect the water system from cold temps. Thoughts I have are to place closed cell foam between the water tank and outside walls, heat tape the water lines, install a light bulb in the compartment where the water line exits the water tank, and heat tape on water tank. Any other ideas others have done?
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Rather than think about opportunities to generate heat with scarce battery power, why not provide a means to move warmed camper air into the space around your water tank in addition to insulating the space between the tank and the outer wall? A small fan forcing air into that space would not consume anywhere near the power of any resistance heater that could heat the water. This assumes that the camper interior is being heated. Anything more complex seems like an unending maintenance issue or a need to provide outside heat/power negating the simplicity of our camper systems. My 2 cents. ;)

Paul
 
Paul we have three active threads that in essence address the topic of heat loss from the camper and hence danger of water freezing in lines or ultimately in the tank. The treads address thermostat issues, Insulation and this one.

I like your idea of heating the "box" outside the interior of the camper by opening a conduit into the area with the water tank and or lines for the furnace heat to keep the water above freezing. No free lunches. Any fan will require amps and of course the furnace requires amps and propane. Energy generation requires energy and short of solar we are carrying a finite amount of energy when dry camping. In the end passive methods of insulation to conserve internal heat by retaining it may be the only viable option. Hell, at -12 here I have a constant struggle to keep the home water lines from freezing.

Perhaps our campers can only retain intact water systems for either a short time with the heater blasting or we clear them of water and carry jugs for extended period during cold weather. Always comes down to the "law of the limits" and what proves to be the bottom line limiter.

Whew...sorry to be so long winded, I enjoy solving puzzles! ;)

Phil
 
I'm a firm believer in the KISS principle. While I don't have the cold environment in Hillsboro you have to deal with it the northeast part of Oregon. (I spent a winter in Joseph upgrading the headrig control system in a now defunct unheated sawmill.) I look at repeatedly winterizing my water system as just a way to avoid chlorine shocking water kept in the tank for long periods. :)

Yes, the fan would use power but 4" fans are available from <1 watt to over 20 watts. For the truly paranoid, there are freeze alarms that could be placed on the water tank to give you time to take action.

Paul
 
If you had and easy way to access the tank, you could use a couple of those chemical hand warmers. They are cheap and last for hours.

cwd
 
I don't have a good idea, but on my trip I took one gallon jugs of water.

I wasn't sure if I wanted to risk water in the tank. The water in the jugs did not freeze in the jug, but immediately froze when I poured it into a mug, and also in a coffee pot. Temps weren't that cold, somewhere in the 20s (I can't remember exactly now, but probably posted it elsewhere).

I kept the jugs of water in the cab of the truck until I was parked for the night so it only became excessively cold overnight. I think the water in the camper tank would have been significantly colder as the ambient temps never got very high (and was not heated while driving like in the cab of the truck). At night, starting from a colder point than a jug which had been in the cab of the truck all day and left on the counter in the heater camper, I imagine the tank would have certainly frozen.

I didn't spend much time considering it after that, but it seemed the tank was right up against the wall of the camper and therefor had almost no insulation from the outside temps. I think there would have to be a lot of insulation added between the tank and camper wall, of which there is little room. There would also need to be a fan or hose directing air from the furnace directly to the tank. Interior "ambient" air would have to be much warmer to overcome the outside temp with the tank so close to the wall of the camper. Bottom line, I don't think it would be a good idea to carry water in the tank in low temps. I don't see there being a good (low power) solution.

What I learned was in order to have drinking water, the jugs had to be carried in the truck during the day and warmed on the stove to drink.
 
My first winter with my Eagle my lines kept freezing on a long trip so I bought and added a fifth of cheap vodka to the 8 or 10 gallon water tank. Since in the winter most of water I consumed was typically boiled for drinks and meals I figured I would be fine since boiling removes a lot of alcohol. Not ideal but kept the water from freezing in 0-10 degree temperatures when I was trying to heat my camper with a little buddy heater. Added bonus the flavor of the vodka masked the taste of the plastic water tank.

Since then I have removed all my plumbing and installed a real furnace.

Now I use 7 gallon water tanks and before I go out skiing in the morning I put a quart of boiling water in each one and cover them with a blanket. I feel if you had a well insulated tank you could put boiling water in it each morning and night and easily keep it from freezing. Would only cost propane and time.
 
It is a tricky Physics question about how cold and how long it takes water of a specific quantity to freeze. Initial temperature of the water is needed along with the conduction factors associated with the container holding the water.

Some thoughts:

1) Water must go through a phase change to transform from liquid to ice. That means that even though it is in an environment at or below freezing it will remain at a constant temperature for a period of time before ice crystals start to form and it begins to freeze (related to the quantity of water and the latent heat of fusion). Recall that farmers use sprinklers to spray water on crops in a mild freeze since the water will protect the plants. In effect the water must give up its latent heat once it has reached the ice phase transition temperature and it remains water thus keeping the temp of the leaves above 32 degrees..

2) If you keep the water above freezing by even a degree it will not freeze.

3) It will take very cold temps in the camper <32 deg plus time to freeze the water. Obviously less time for colder temps and longer time for warmer temps. A so called hard or prolonged freeze is where i start to be concerned. A hard freeze usually means temperatures falling into the upper 20s or lower for at least two to three hours. A prolonged freeze are temps below 32 degrees for more than four hours.


4) If the camper is above freezing the conduction though the container bottom would have to be very high since 4 sides and the top of the water tank will be exposed to above freezing temps from the inside of the camper. I think even a small amount of foam insulation would make a big difference here. even a piece of wood, the bottom floor of the camper, probably slows the heat loss down sufficiently. Loss of heat through the bottom of the tank will probably not be an issue until the outside temps are less than 20 degrees and probably lower than that is required.

5) if the camper temp drops below freezing the water will eventually freeze. If the water is already near freezing it will happen faster than if it is not.

So keep the inside of the camper above the freezing point of water - 32 degrees (0 C). I have a thermostat in my camper that is intended for a space like a garage that can be cold but that you don't want to freeze. Its lowest set point is 35 degrees. As long as there is propane and the heater in the camper is functional I don't think the water in the tank can freeze.

If camping in really cold conditions where outside temps are below freezing all day and/or overnight temps drop well below 20 degrees then it may make sense to add a low wattage heater blanket to the tank (assuming you can handle the power draw somehow) or not use or have water in the tank.

The danger from water is the expansion of the volume when it turns to ice. That expansion is about 9%. So if the tank is less than 3/4 full and the air in it can escape then the ice will expand into the available volume (by 9%) and have plenty of room without cracking the sides. Hoses that could freeze would have to be drained however as the same issue applies there.

I hope this is of some use.

Regards,

Craig
 
ckent323 said:
I think even a small amount of foam insulation would make a big difference here. even a piece of wood, the bottom floor of the camper, probably slows the heat loss down sufficiently. Loss of heat through the bottom of the tank will probably not be an issue until the outside temps are less than 20 degrees and probably lower than that is required.
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During our Hawk Flatbed install last October I taped 3/4" rigid foam between the 5/8" plywood "runners" under the Hawk's floor. I believe there were four spaces about 12"-14" wide that ran the full length of the camper. Hopefully this will help heat loss and make the inside more comfortable. I'm sure Denny thought I was crazy but he was very patient. For the cost of a sheet of rigid insulation it seemed like a good idea.
 
One thing to consider, and seems to have been said though not widely noted, is that the water in the pipes and hoses will freeze first. Long before the tank does. Less insulation there, and less total BTU's to remove before it freezes.

Our recent T-day trip to the Alabamas illustrated this. Lows overnight into the mid teens, low inside (malfunctioning heater) mid 30's. All water fine, but the sink drain froze solid both nights and the drain bucket had a thick sheet on top (in spite of the soap and various suspended particulates).

Based on this, my first worry for freezing is the water tank's drain hose, which is outside and exposed. I shall likely enclose it in some A/C insulating foam.
 
Craig, I don't think it's that easy. The water tank isn't near the thermostat, so the tank isn't as warm as the rest of the camper. With all of the cabinets between the tank and the rest of the interior it's almost insulated from the warm furnace air. It is closer to the skin of the camper, which is much colder and closer to the outside temp. The interior (where you might walk or sleep) of the camper can be well above freezing, but I don't think that means the tank will necessarily be above freezing.
 
Wow...more great ideas to prevent freezing of our water lines and storage tank.

First Craig, when we deal with single digit temps and below zero nights or days, even a slight differential between inside camper temps and temps between the camper walls and inside box will be critical...nominal winter temps out here are a high of 20 and a low of -10; with sunshine! An uninsulated box without a hell of a lot of internal heat will freeze all water within.

I do like the concept of putting foam board strips under the Hawk when we take delivery in Feb, that can only help lessen the heat loss out the base of the camper...IF all FWC campers have these runner spaces to put the foam into, I have no idea if all FWC campers have these runners [again, my take on a weakness with FWC, is the lack of details on construction and design]...secondly, I like the approach of insulating the components from the outside walls as best as you can....again, my choice is 2" DOW foam board if that will work in the space available.. of course this insulation inside the outside shell will only work if interior 'box' heat makes it into the space with the plumbing. Insulation only keeps heat in.

Last two options that might allow a retention of any water within the camper plumbing or storage tank and thereby give us a functional system of water outlets is the use of electrical heat wrap or 'blanket' assuming that with two camper batteries and solar panels I can "afford" the current draw.

The other possibility is to leave an opening, if there is one [again no word from FWC], from the inside tub/box of the camper into the area with the plumbing/tank and leave the heater running at whatever temp is required to prevent the water from freezing. Of course as previously mentioned the heater uses propane and battery power. No free lunch if you want to have water to use in the camper.

Soooo. When I asked FWC about using our new Hawk during the winter the response I got was: "Just leave the heater on the low set of 40 degrees and nothing will freeze". Hmmmm...Like Ace sez that will not work during really low temps and or over prolonged periods of low temps.

I am hoping that I don't have to make my FWC a "three season" camper as I want to use the external shower, inside faucet/sink and hot water heater I purchased. Yes, I can and may have to drain all water from the camper and simply carry jugs of water for cooking, washing and drinking.

Honestly, venting a little, for the cost of the Hawk not having a functional water system during any below freezing temps sucks!

Do appreciate the positive, can-do, attempt of the folks on this forum trying to figure out a 'work around'...very cool.

Thanks to all,

Phil
 
Wallowa said:
....again, my choice is 2" DOW foam board if that will work in the space available..
Phil
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I don't want to rain on your parade, Phil, and it depends on your vehicle. But at least with my slide-in Hawk and my 2012 Ram 2500 there wasn't more than 1" space (if that) between the wheel wells and the camper side walls.

You will really like your Hawk.

Steve
 
Steve,

Thanks for that....my intention is not to add insulation between the box and the area immediately adjacent to the wheel wells. For one that contact, or almost contact space and the area is very small as you pointed out.

I hope to insulate the following areas: [Note: These are all TBA and may not prove to be feasible]

#1 Inside the camper against the outside shell/walls of the camper; where I have access and space for the foam board.

#2 Between the rails/runners on the bottom of the Hawk; if they exist on the Hawk, no FWC source of info on that construction.

#3 On the outside sides of the camper box inside the truck bed.

#4 Outside under the camper overhang on the sides of the camper.

#5 In the alcove areas of the Tundra truck bed adjacent to the camper box.

#6 Inside the camper under the roof panel with cut outs for the two roof vents.

#7 Over the forward cab window and any other windows not in use; slide in foam boards.

All of this may prove to be for naught and truly protecting the water systems inside the camper may prove to be impossible during winter low temps we experience out here. I have an infrared heat sensor that will be used to map out where I am loosing heat and hopefully, post installation of the insulation, determine how effectively the insulation is working.

But what the hell, I love a good challenge! ;)

Phil
 
I'll be very interested to see where you lose the most heat. That's a great idea.
 
Maybe MarkBC can find his post when he used the infrared camera. It was surprising to me to see where the heat loss was.
Never frozen the main tank but I've frozen the drain a few times, never seemed to do any damage.
 
I believe the poly material of water tubing will expand enough to not fail as the ice reaches it max expansion [which I seem to remember occurs just at or slightly below the freezing point]; now I have no idea what the water storage tank material is.

Solid fixtures and pumps are the points that will fracture if the ice can not expand out of them.

Can anybody with a Hawk verify for me the presence of the runners and inter-runner spaces under the Hawk box? Length, width and depth? If my new Hawk will have them, I plan to pre-fab the foam sheet insulation to place into these space when I pick up my camper.

Thanks,

Phil
 
It would be interesting if someone in a cold environment (I am not) could perform an experiment to provide some empirical data.

I am thinking of an indoor outdoor type thermometer with wireless (or wired probe on a cord) which has a min max memory, or better yet a recording type thermometer setup, with the outdoor probe in the water tank compartment to measure the temperature at the lowest accessible point overnight on a cold night along with the camper interior temp at the top of the water compartment as well as the outside temp.

This could be repeated in several locations and with various "maintenance temp" thermostat settings as well. With sufficient data (at least 3 or four data samples at different well spaced temperatures for each location) a chart or two could be constructed and a curve fit to the data that one could use to make projections about outdoor temps vs water tank compartment temps vs interior temps.

Of course this would probably be done with the water tank empty which would be a worst case scenario without a mass of water in the tank that would have to be cooled down before freezing,

Perhaps another Engineer/Scientist/Physicist in the group will have some suggestions for doing this and maybe someone will actually perform the experiment.


Regards,

Craig
 
You might consider boiling water, filling a container with the hot water, wrap in a towel to slow heat loss to extend the time, and put it into a cabinet that you want to keep from freezing overnight. A rubber hot water bottle is flexible and could be placed close to a water line in a pinch. Adapt and innovate. Any water used in the container could be reheated & reused.

Use the hot water bottle to warm your feet or your SO if not needed for your water lines. :)

Paul
 
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