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2017 PM2500, 159"WB
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Discussion Starter · #1 ·
Red X marks heater and vent location, water tank sits over wheel well. Wheel well is enclosed in a box, I filled all remaining void inside that box with closed cell spray foam.
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What are some ways to help keep you water tank from freezing when vanning in the winter months? How much of an issue is this if you are living full time in the van with a heat source?

I'll be living in the van on some ski trips this winter. I have a 21 gallon water tank located under my bed which is open to the rest of the living area which is heated by a 5kw diesel parking heater. I'm hoping that regular use and heating the van at night will be enough but im not sure. I have 1" polyiso under my floor and about 1" of closed cell spray foam all around the rest of the van. I'm debating running to additional duct work over to the tank to ensure it gets some direct hot air but im not even sure thats worth it. I also read about putting some objects in the tank to help disturb the surface enough to keep ice from forming, floating plastic balls or something similar.

In hindsight I could see a design where the water tank compartment sits over the diesel heater being more helpful.
 

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2016 136WB low roof diesel, converted to an RV by Sportsmobile, TX
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If the tank is exposed to the heated space, it should be fine. It takes the loss of a lot of heat to freeze water, so it would have to be below freezing for a long time for the water to freeze. If you are really worried, run a loop of copper tubing in the airstream of the heater, with one side connected to the water pump through a valve, and the other side going into the unpressurized tank. Once in a while when the heat is running open the valve a crack for a while, and let the water pump push water through the loop to heat it a bit.
 

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Depending on how/where it runs, a water line may be more likely to freeze on very cold days while you're out skiing.
 

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2014, 138WB, High Roof, Gas, SW MT
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Hi,
You might want to take a look at the approach we used to prevent freeze problems...

The basic approach is to insulate the water tank and provide a quick way to drain the plumbing.

Due to the large thermal mass of the water in the tank and its low heat loss through the tank insulation, it will take a very long time to freeze even if the van goes fully cold (there is a time estimate at the link above).

The big problem is the plumbing, which will freeze pretty quickly and often runs through cold parts of the van. Our approach to this is to have a quick way to drain the plumbing (see link). If you don't provide some means to prevent it, your plumbing will likely be much more of a freeze problem than your tank.

We wanted to be able to let the van go cold and still not have the water system freeze up. This allows to (for example) stay a night in a motel without worrying about leaving the furnace running in the parking lot all night. Having our water system freeze solid if there was some kind of failure of the heating system was not something we wanted to deal with.

Gary
 

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2018 ProMaster 3500 159" extended Fulltime 4 season van build
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May want to look at Class A Customs Auto Thermostatic controlled heat pad. $29 I installed one on my tank which is above my wheel well and is exposed to my garage storage space. I fused it's own circuit so I can control. As others have noted that the water lines would be more at risk first. My thought is that if the tank maintains 50 or so degrees it will likely keep your water lines safe unless you've got water lines close to colder spots in the van.
 

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2014, 138WB, High Roof, Gas, SW MT
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May want to look at Class A Customs Auto Thermostatic controlled heat pad. $29 I installed one on my tank which is above my wheel well and is exposed to my garage storage space. I fused it's own circuit so I can control. As others have noted that the water lines would be more at risk first. My thought is that if the tank maintains 50 or so degrees it will likely keep your water lines safe unless you've got water lines close to colder spots in the van.
Hi,
The heating pad sounds like a good plan.

But, I don't think keeping the water in the tank above any temp will help keep the pipes from freezing.
Once the water stops flowing in the pipes, it does not have much mass and will cool quickly to whatever temp surrounds the pipe. We have one pipe that goes across the van in the floor, and even though it has some insulation under it, it freezes pretty quickly if the outside temps are cold. We have to drain the plumbing in cold weather to keep it from freezing. Once the pipe freezes, it takes a long time to unfreeze it with the furnace going. We had one trip in cold weather where the cross floor pipe froze on the first day, and we never got it to thaw for the whole trip.

Gary
 

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Any body use this:

Heatti had 6 feet pipe heating cable with built in thermostat. $21.99

Heat tape

Not sure how much draw
Seems KOA s use something for their pipes at site

Sent from my LG-H871 using Tapatalk
 

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I'd bet my life that you'll never freeze even a plumbing line that is inside the van while you're using it. We're in southwest Montana right now. Had the interior of the van at 65 when we went to sleep at midnight on Monday night and didn't run the heat until 7am. The temp in the van was 40 degrees. It was about 15 degrees outside with single digit wind chills outside. Wind was blowing 35mph+.

Josh
 

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Discussion Starter · #9 ·
I'd bet my life that you'll never freeze even a plumbing line that is inside the van while you're using it. We're in southwest Montana right now. Had the interior of the van at 65 when we went to sleep at midnight on Monday night and didn't run the heat until 7am. The temp in the van was 40 degrees. It was about 15 degrees outside with single digit wind chills outside. Wind was blowing 35mph+.

Josh
Thanks, this is what I was hoping to hear. In the past (in last van) I would usually run the heater until im going to sleep, and fire it up again in the morning. I will probably still do something to make it easy to clear the pump without draining the water tank.

I might also swap out my normal 7 gallon grey water tank (blue reliance tank) for something like a 5 gallon bucket so I can easily take the lid off and knock out the frozen grey water if necessary.
 

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Thanks, this is what I was hoping to hear. In the past (in last van) I would usually run the heater until im going to sleep, and fire it up again in the morning. I will probably still do something to make it easy to clear the pump without draining the water tank.

I might also swap out my normal 7 gallon grey water tank (blue reliance tank) for something like a 5 gallon bucket so I can easily take the lid off and knock out the frozen grey water if necessary.
I have a grey water tank mounted under the van with a bypass for nights when it's going to be really cold. I forgot to open it twice this trip 😁.
 

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We're planning to do some cold-weather camping with our van and we just purchased a multicontrol for our Webasto. We plan to use this to run our heater as varying intervals during the day/night when we are out and about so that the van stays warm enough to keep the pipes and water from freezing. We'll see how well it works!
 

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2014, 138WB, High Roof, Gas, SW MT
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Hi,
What you do for freeze protection is of course 110% up to you, but here is another data point to look at - a cold weather trip up to Banff
Our water supply line across the floor with insulation under it froze up on the first day and we were never able to get it to thaw on the whole trip. The van was heated by either the car heater (driving) or the furnace at night the whole time. This was really cold weather (-10F ish), but if you go on ski trips you will likely see the same once in a while.

We also had the same line freeze up on a winter trip from Montana (where we live) down to the gulf. It did thaw out once we got out of the cold weather on the way south. Again, the van was occupied and heated the full time.

Its very easy to add freeze protection when you are building and often really hard to add it after the build is done.

Gary
 

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Discussion Starter · #13 ·
Hi,
What you do for freeze protection is of course 110% up to you, but here is another data point to look at - a cold weather trip up to Banff
Our water supply line across the floor with insulation under it froze up on the first day and we were never able to get it to thaw on the whole trip. The van was heated by either the car heater (driving) or the furnace at night the whole time. This was really cold weather (-10F ish), but if you go on ski trips you will likely see the same once in a while.

We also had the same line freeze up on a winter trip from Montana (where we live) down to the gulf. It did thaw out once we got out of the cold weather on the way south. Again, the van was occupied and heated the full time.

Its very easy to add freeze protection when you are building and often really hard to add it after the build is done.

Gary
Thanks gary, I am definitely anticipating some extreme cold, I come from northern Vermont where we see -20 in the heart of winter. I plan to borrow from your playbook and design a way to clear the lines without draining the tank and just regularly keep an eye on projected temperatures. Luckily extreme cold snaps dont usually come out of nowhere but I think thats about the best I can do short of one of these electric heating pads/tape people are recommending. I dont have (and nor do I want) the battery bank to support such an option.

Worst case is I just stop using the main water supply and faucet and use secondary jugs to manually pour water as I need it. This was my solution in my first van while spending a winter in new england. Not as homey but as I often remind my gf, dont think of the van is not an alternative to a house, think of it as an alternative to camping😂
 

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Hi,
What you do for freeze protection is of course 110% up to you, but here is another data point to look at - a cold weather trip up to Banff
Our water supply line across the floor with insulation under it froze up on the first day and we were never able to get it to thaw on the whole trip. The van was heated by either the car heater (driving) or the furnace at night the whole time. This was really cold weather (-10F ish), but if you go on ski trips you will likely see the same once in a while.

We also had the same line freeze up on a winter trip from Montana (where we live) down to the gulf. It did thaw out once we got out of the cold weather on the way south. Again, the van was occupied and heated the full time.

Its very easy to add freeze protection when you are building and often really hard to add it after the build is done.

Gary
I'd say this is a design flaw Gary 😁. That's kind of like running a water line through the attic.
 

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2014, 138WB, High Roof, Gas, SW MT
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I'd say this is a design flaw Gary 😁. That's kind of like running a water line through the attic.
The line does have insulation under it, but apparently not enough.
Its kind of hard to get a plumbing line from one side of the van to the other without going through a place where its going to be close to the floor or ceiling.
Had I thought about it a bit more, I'd have put the tank on the same side as the galley, or run a heater wire along the pipe, but hard to do now.
Frozen pipes in RVs are pretty common.

Gary
 

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I think insulating the tank is the best option..well that's what worked for me.
 

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I think insulating the tank is the best option..well that's what worked for me.
You'd have to have frigid temps for an extended period to freeze your tank. As Gary noted, water lines in places that don't get heat would be your problem. It's best to avoid this during the design if possible.

One thing I would attempt to change if I did another build would be the cold floor. Don't know if there's much you can do about that though.
 

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2016 136WB low roof diesel, converted to an RV by Sportsmobile, TX
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If you are that concerned, you could create a loop - run a line from just at the faucet back to the tank, entering the unpressurized tank, then have a valve between that line and the pressurized line. Crack the valve, and you have a "drip" that does not waste water - you have circulation through the lines to keep them from freezing. It does mean your pump will be firing off once in a while, but if you have a pressure accumulator that won't be very often.
 

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The line does have insulation under it, but apparently not enough.
Its kind of hard to get a plumbing line from one side of the van to the other without going through a place where its going to be close to the floor or ceiling.
Had I thought about it a bit more, I'd have put the tank on the same side as the galley, or run a heater wire along the pipe, but hard to do now.
Frozen pipes in RVs are pretty common.

Gary
On my new build I have wheel well tanks both sides & thus will need a cross over pipe. This pipe will be run inside “warm side” & under the bed area.

One of the nicest floors I have seen on here had a pex pipe under floor. I get the attraction, but I just can not bring myself to do it.
 
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