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Old 10-29-2015, 10:08 PM   #1
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Question Optimal water system for frequent sub zero temperatures?

We're nearing that plumbing portion of the conversion, and starting to sketch out the final plan for the project. Our goal is to have a simplistic water system that can remain semi-functional through sub zero temps with little/no power consumption needs. We are definitely willing to change our water transport process, but we want to avoid the need for full winterization of the plumbing if we decide to leave the bus vacant for a week in the winter.

Heating the bus via a small space heater while gone seems risky, and also impractical seeing as our power will be solar/battery bank, although it would pretty much solve all of our problems. the design below is an attempt at avoiding the space heater approach, but if someone thinks it can be done well - we would love to hear more.

Here is the rough design so far - sorry it's upside down:

Long story short - 12v DC water pump. pulls water via a T split (not shown in drawing), one source being a 25 gal "raw" water tank mounted underneath the bus, the other being basically a garden hose spigot, so that water can also be pumped from a pot of warm water on the stove via a hose. both sources have on/off vales in line, and only 1 of the 2 should ever be open when the pump is on.

On the output side of the pump, I also have a T split. One path leads to the top bucket of a 2 stacked bucket gravity ceramic filtration system, and the other to a shower head mounted on the ceiling.

The top bucket of the filtration system directs water through a ceramic filter and into the bottom "clean" bucket. Then, the potable water is pulled through the faucet via a whale "babyfoot" galley pump where it drains down into a gray tank via pvc below the bus. The shower will also drain to the same gray tank via reinforced hose.

For sub zero temps I'm thinking we will drain the raw 25-gal tank into smaller jugs, and manually fill the top bucket of the filter system during the winter. The filter, buckets and pump will be easily accessible, but hidden in an insulated cabinet with a small incandescent bulb. we hope the bulb will produce enough heat to prevent everything inside the cabinet from freezing if we are gone for a few days during the winter, but will also not draw too much from our battery bank.

The gray tank will have new rv antifreeze added each time it's emptied.

The shower drain will be webbed vinyl hose to avoid freezing pipe problems, and will probably have an inline on/off valve to serve as a p-trap. we could probably also get away with a nice closing drain cover on the floor of the shower.

Does anyone know if you can completely clear out your water lines by removing the water source, but continuing to operate the pump?

If so, I'm thinking I can install another T with on/off valves, just after the water leaves the clean bucket. This way I can shut off the water at the clean bucket, open the other valve to let in air, and pump out the residual water with the foot pump through the faucet. I could also pull the inlet hose out of the pot of hot water after showering, and run the pump for 5 sec to clear the excess water out. Would that be a way to avoid frozen pipes/hose?

I'm also still stumped on how to prevent the p-trap under the sink from freezing up if we are gone for the day. Longer periods of being away - we'll just add antifreeze, but I don't want to have to add it every day I'm gone for 8 hrs in the winter....we could potentially use another small light near the pipe, or add a drain valve in the p-trap (which would probably leak). Or maybe even put a few lava rocks, heated up on the wood stove underneath the sink in a bowl of sand....

Any ideas?! is offline   Reply With Quote
Old 10-30-2015, 05:07 PM   #2
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Hepvo makes a neat waterless sink trap.

Hepvo Waterless Valve

I set up my water system with the tank on one end and the water heater on the other. The tank and heater are the low points with the PEX piping sloping up to the center point between them so there is no low spot in the piping and water would naturally drain to each end when I drain the system. It works fairly well but there is still a fair amount of water left in my Atwood water heater after draining it.

There is also a strainer at the water pump inlet that has to be manually drained.
The strainer issue could be fixed by remounting my pump. Not sure if the remaining water in the water heater would be a problem but I hesitate to tempt that particular fate.

If you have air brakes maybe you could make a hookup to the water system so you could blow it dry with compressed air. Not sure how clean brake system air is though.
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Old 10-30-2015, 07:42 PM   #3
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Those waterless traps at first glance seem expensive but, firstly how many do you need 3-5 of them. Then you realize how much flexibility it gives you in your designs.

As someone who grew up in the midwest and in a house that suffered many power outages. The only way to insure you won't freeze over is to add more heat.
Insulating the tanks and using a water bed heater (not a lightbulb you don't need light you need heat) will do it set up a thermostat so it only kicks on at say 34 degrees. If you don't want to have your plumbing runs inside then you need to insulate them and probably run a heat tape along them.

You mentioned solar and leaving the bus. If your system works well, and you are not in it drawing the loads, then there should be plenty of excess power to keep you wet stuff from freezing. Also how cold and how long? The other option is sizing your battery and solar correctly to handle the load of keeping your liquids liquid. I don't think you have a water system problem to solve. I think you have a power system problem to solve.

Remember living well for free/cheap costs a bit upfront. Its like with socks you can buy a bunch of cheap ones that will last you a couple of months each or buy a pair of really nice wool ones that will last you years. If you are in it for the long haul build/ plan accordingly.
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Old 10-30-2015, 09:00 PM   #4
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Seriously, you want us to stand on our head to read what's on your picture?
I'm hungry!

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Old 10-30-2015, 09:52 PM   #5
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That's funny CC. I didn't even notice it. Seems I read just as well upside down as right side up (which isn't saying much), a situation which has repeatedly caused me trouble reading a map. Thank goodness for Mapquest!
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Old 11-01-2015, 11:11 AM   #6
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Thanks for all the info!

Roach - that waterless P trap is perfect! I only need 1 for the sink, and am perfectly OK with manually opening/closing a valve for the sink drain p-trap. I wont use the shower nearly as much as the sink. I should be OK with the pump strainer since the pump will be inside of the water filtration cabinet, which will be somehow heated while Im gone. Love the air brakes idea - might work perfectly for clearing the shower lines and not burning my pump engine out! Thanks!

CaptainInsaneo - totally hear ya on the "power problem, not plumbing problem." Just looked into electric blankets and it doesn't seem like small ones draw TOO much more power than a 100w incandescent bulb. Some also have built in thermostats, so that could be the perfect solution.

The typical winter scenario I'm thinking about is leaving the bus 6AMish, and returning after the lifts close the same day, around 5PM. Not that long of a time, but, it's really hard for me to predict how well the bus will hold heat once it's finished (walls and floor clad in wood etc). I also expect to do a bit of winter camping, and could need to leave the bus for a week. I'm really looking for some flexibility.

Home base is in IL, so the system has to be able to handle cold Midwest winters even though I will likely spend the majority of the winter somewhere milder like CO.

Also saw one of these little space heaters online:
maybe I could run that on a thermostat while gone and keep the whole bus +32F?
Again, hard to say before the bus is done.

CC - sorry about the picture, not sure why its flipped in the thread. Try this link instead:

I'm all for doing it right and spending a little more up front if necessary, so keep the suggestions coming! Thanks again! is offline   Reply With Quote
Old 11-01-2015, 11:42 AM   #7
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There are far cheaper and longer lasting sources of heat for off grid than electricity.

If you have the $$ for the infrastructure, electricity is best.

How about a simple coal stove? Load it once or twice a day and be warm all the time for cheap.

I lived in my tool shed for 8 months the winter of 2014/2015. It gets -40C here. I burned under two tons of coal for a cost of under $100 for the entire year.

We also heated bath water, cooked, ect all using the coal heat.

You want simple, forget about pipes.

Shower with a bag of heated water from the large pan on the coal stove.

Empty shower water via a 5 gallon pail.

Sink works the same way, a dipper to dip warm water from the large pan on the stove.

Nothing to freeze, stop working and break.

This is how I grew up. I never saw plumbing pipes till I left home at 15 years old.

"Don't argue with stupid people. They will just drag you down to their level, and beat you up with experience."

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freeze, kitchen, plumbing, water, winter

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