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I'm still in an early stage of my build where modification to my water system is easy. I'm hoping to use my rig for winter ski trips (3-10 days).

I have insulation and heat sorted. My plan for water is below. Anything I'm missing in terms of making sure the water system works in the winter?

All plumbing internal. Outside shower will be housed/accessed from the garage, thus no parts to freeze. Water tank accessed from the garage to fill, thus no fill port to freeze. All plumbing interior in heated part of the van, with any sections that are partitioned off ducted to provide heat.

The ONLY plumbing that is exterior is my 20 gallon grey tank. My theory is that the small run going through the floor into the tank won't freeze when waste water is running into the tank. Additionally, once water reaches the tank as long as the tank doesn't fill up it is generally OK for the waste water to freeze at the bottom of the tank. I realize I could use a heating pad or antifreeze.

Anything I'm forgetting about the water system? Anything I should keep in mind when preparing a fully winter-capable water system (showers and sink water)? Thanks
 

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I think the weak link will be the heater not the water system. You may have to keep heater running full time. What heater? How will u heat water? I've found that 200watts solar and 220Ah battery won't keep up with constant heater, fridge, lights, phone/computer charging, and winter sun. You can let inside cool down during day but re-warming everything at night may not save energy.
 

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I think the weak link will be the heater not the water system. You may have to keep heater running full time. What heater? How will u heat water? I've found that 200watts solar and 220Ah battery won't keep up with constant heater, fridge, lights, phone/computer charging, and winter sun. You can let inside cool down during day but re-warming everything at night may not save energy.
The air heater will likely not have to run full time. With an adequately insulated camper, keeping the rig comfortable (50-60) shouldn't place that big of a demand in terms of heating BTU's. Heating BTU's are cheap with a fossil fuel. I have a Propex HS2800-1.9aH running full time.

IF it ran full time, and that's a huge/unlikely IF in average 15-30 degree nights, it would use 48aH/day. I have a Isotherm 85 and will install the smart energy control, so call all my other energy demands (liberally) 30aH/day. That's 78aH/day.

Will my 300aH bank/360watt solar array keep up? That's the real question ;). I hope so. Anyone able to chime in on winter sun solar output?

The hot water heater is a regular suburban propane tank unit. With 5.5 gallons of propane on board, I'll have plenty to keep the hot water warm enough not to freeze and then crank it up when it's time for a shower.
 

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Your propane stores could also be a limiting item. The Propex HS2800 has a burn rate of 10 hours per gallon, that's 55 hours. So ignoring your cooking and water heating needs, a ten day trip is 240 hours so you have a max duty cycle of around 23%. Or as you say 55 hours (2 days 7 hours) in the unlikely event that it would run 100% of the time. Might be a race between running out of propane or your battery half-life AH in that situation.

Not sure what your cooking or hot water needs are, but I'd certainly fill my propane tank before going on an extended trip or if I knew it was going to be cold.
 

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Plan a nice warm drive every other day to recharge the batteries and to go for propane. Your solar will be somewhat more efficient in the cold but the hours of usable light and the low sun angle work against you. Tilting panels could help if you add a ladder and park for days.
 

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Your capacities seem adequate. With your projected needs I'd consider a shunt and good monitor. No-one has reported issues with occasional short term idling to top your batteries and save some propane. Lots of ways to augment energy supplies. A gas buddy is good insurance, takes up little space, and will get you through a night.
 

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2014, 138WB, High Roof, Gas, SW MT
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Hi,
Just came back from a winter trip up to Banff area in our PM, so thinking about the same issues.

Based on past winter trips, I think your grey water tank can freeze is probably OK. We have come back home from past winter trips with the grey water tank frozen -- I think as long as its not full it will take being frozen. Have never had the plumbing leading to it freeze. You can dose the grey water tank with some RV antifreeze at start of trip to make it less likely to freeze, but its still going to freeze if the weather is really cold.
Do you have a way to determine that the grey water tank is not full, Because, if it is full and it freezes, it will destroy the tank for sure.

Just as a data point, we kept track of propane use on one winter trip and with night temps in low 20's, we used about 0.6 gallons of propane per night.
http://www.buildagreenrv.com/trip-reports-experiences-and-lessons/banff-trip/
Our van is well insulated.

So, depending on the size of your propane tank, the keeping the van heated with the propane furnace might be workable.
Like yours, all of my plumbing (which is basically just the plumbing from tank to pump and from pump to sink is inside.

Based on a few winter trips, I am looking for a way that I can rely less on the furnace. I don't like wasting the propane and being dependent on the furnace working all the time. Right now, if we want to stay in a motel for a night, I have to leave the furnace on all night to keep things from freezing -- just seems wasteful and not very robust. My fresh water tank and pump are right next to each other, and I think that with some insulation around them a small electric heater could keep them from freezing. I think that I can work out a simple way to drain the plumbing line that goes to the sink fairly easily. This would allow us to let the van go cold with just a small electric heater to keep the pump and tank from freezing -- a heater that can be powered by the house battery.
http://www.buildagreenrv.com/our-co...-plumbing-and-the-fresh-and-grey-water-tanks/


I can tell you from personal experience that the diaphragm pumps commonly used on RVs are not at all freeze tolerant, so be sure whatever scheme you use protects the pump.

Solar output in the winter with the low sun and more cloudy weather is poor. Tilting the panels will definitely help and is probably worth the effort if you plan a lot of winter trips.
Snow cover on the solar panels will cut their output to near zero and it does not take much snow to do this. You have to keep the solar panels free of snow if you want any useful output from them.
My van sits in the driveway all winter in Montana, and we have found that an inch or two of snow on the panels and our 315 watt solar panel will not keep the batteries up even with all of the significant electrical loads disconnected.

I think that if you plan to rely on your battery and solar to keep the furnace or heaters running, then you want to invest in a battery monitor system so you can tell at a glance how much juice is left.
http://www.buildagreenrv.com/our-co...solar/battery-monitor-how-much-juice-is-left/

Our procedure when we get back from a winter trip is to..
- Drain the fresh water tank -- have a drain line with valve for this.
- Run the pump with sink faucet open until it starts spitting air.
- Disconnect the input and out hoses from the pump (see pic at link above
- Run the pump for a few seconds to make sure its clear of water.

We do this before the van has a chance to cool down, and this has worked fine. But, if we forget, and the pump freezes, it will total it.

As I'm sure you know, while winter ski trip nightly lows are likely to be 20 ish, you can run into an occasional spell of really cold weather -- like -20F, and this will put your whole system under much more stress and would make a backup system that allows the van to go cold very valuable.

I would try to work out a system that allows you to easily drain all your internal plumbing and the pump easily -- just as a backup if nothing else.

Gary
 

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So a question on the van just sitting and outside temps. Mine is pretty well insulated and all my tanks are inside. I've got the standard pump/vinyl tubing, and then a 25 gallon fresh and 5 gallon grey. Do I need to worry about mid 20s temps outside? When I go out of town for a couple of weeks soon, I was going to drain everything and run the pump dry, as that would take like 15 mins of my life. Wondering if I need to do that this week, as I'm going to use the van again this weekend. Maybe I should just set the Webasto at 40 degrees and not worry about it?
 

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The ONLY plumbing that is exterior is my 20 gallon grey tank. My theory is that the small run going through the floor into the tank won't freeze when waste water is running into the tank. Additionally, once water reaches the tank as long as the tank doesn't fill up it is generally OK for the waste water to freeze at the bottom of the tank. I realize I could use a heating pad or antifreeze.
Make sure you don't have any low spots or horizontal runs in the drain line where water can collect, freeze and plug it. Vans aren't always parked level. Dumping some antifreeze in at every use would help but that stuff sort of stinks.

A few inches of solid ice in the bottom of a tank could cause it to split open. Water expands when it becomes ice.
 

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2014, 138WB, High Roof, Gas, SW MT
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So a question on the van just sitting and outside temps. Mine is pretty well insulated and all my tanks are inside. I've got the standard pump/vinyl tubing, and then a 25 gallon fresh and 5 gallon grey. Do I need to worry about mid 20s temps outside? When I go out of town for a couple of weeks soon, I was going to drain everything and run the pump dry, as that would take like 15 mins of my life. Wondering if I need to do that this week, as I'm going to use the van again this weekend. Maybe I should just set the Webasto at 40 degrees and not worry about it?
Hi,
The tank will take a long time to freeze, but the plumbing and the pump can freeze pretty quickly.

For this last trip, I put water in the fresh tank the day before because I thought it would be OK overnight, but just one night in the 20'sF froze the plumbing to the sink. No damage was done in this case, but it took a full day of driving with furnace on in back and cabinets open to get it thawed. A couple days in the 20's F would freeze all our plumbing and pump solid.

I would just make a habit of draining the tanks and the plumbing right after each trip in the winter. Takes me less than 5 minutes. Open fresh tank drain, do something else while its draining, open faucet and run pump until faucet spits out water and air mix - this gets enough water out of the plumbing so any remaining water in lines won't do any damage when it freezes, then disconnect the quick connect hoses to the pump and run the pump for a couple seconds to make sure its free of water. No antifreeze needed.

I think pex plumbing with minimal use of fittings is good for freeze resistant to freezing. Runs between metal fittings give the ice a hard place to push against so the ice can't expand along the line.

Gary
 

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Hi,
Thinking about this more overnight, I am going to try this approach to freeze protection of the water system.

If we are in the van most of the time, then just use the furnace to keep us and the water system warm.

If we want to leave the van for an extended period and don't want to trust the furnace left on to keep the warm and don't want to waste the propane, then use an arrangement that drains the plumbing and pump, insulate the fresh tank, and use a small electric immersion heater in the tank on a thermostat that keeps tank water above freezing.

Do this by;

- Add a valve in the plumbing line between fresh water tank and pump inlet as close to the tank as possible.

- Add a Tee to the line between the tank and pump inlet. The branch of the Tee has a valve in it and then a short line that drains down through the floor.


To drain the plumbing
- close the valve that is near the tank .

- open the valve in the new drain line.

- open our sink faucet and run the pump until mostly air with only a little water is coming out of the sink. The pump will be pulling air throughthe new open valve in the pump inlet line.

- repeat for any other faucets or the shower.

- This may be enough, but I will probably also disconnect the quick connect pump inlet and outlet hoses.

- Turn on the fresh water tank heater.


I don't plan to try to protect the grey water tank as I've had two RVs now where we let it freeze when its only part full and have not had any damage. The open space above the water gives the ice a place to expand -- but, there may be some tank geometries where this does not work. I guess add RV antifreeze if in doubt.


How big does the fresh water tank heater need to be;

A typical 20 gallon fresh water tank has about 25 sqft of surface area.

If its insulated to R10, which is about 1.5 inches of polyiso.

Then, the heat loss from this insulated tank is about 2.5 BTU per hour per deg F.

So, if the tank water is at 32F and the outside temperature is 20F, the heat loss is about 30 BTU/hr or 9 watts.

If the tank water is at 32F and the outside temperature is -20F, the heat loss is about 130 BTU/hr or 38 watts.

So, for normal sort of conditions in the 20'sF the heater draw would average about 9 watts or less than an amp.

For extreme -20F conditions the heater draw would average 38 watts or about 3 amps.

Something like a 50 watt heater that would only run about a quarter of the time under mid 20's conditions seems about right to me.

The insulation on the tank is key here -- without it, the heat loss would be about 10X more and an electrical heater would probably be impractical.

The thing I like about this setup is that if you want to leave the van for a day or two you don't have to leave the furnace running and wasting propane, and if the furnace fails, you have a backup.

Another thing to bear in mind is that even if the tank electric heater fails, the tank will take a long time to freeze into a solid block of ice. If you have a lb of water at 32F, it takes 144 BTU to turn it into ice. To freeze the whole 20 gallon tank would take about 24,000 BTU of heat loss. With the insulated tank, and 0F outside with no tank heat, it would take more than a week to freeze it solid. The plumbing and pump freeze fast because the low mass and no insulation, but the insulated tank will be slow to freeze.

Gary
 
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