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....