Plumbing and Hot Water System
While I have been building the van, I have gone back and forth on how to do the water system. I considered the traditional RV type system (large water tank, propane water heater, etc), but I didnt want to add propane and there was not a good place to install a large water tank in the van.
I always try to learn from others, so my water system is a combination of the water supply system from OurKaravan
with an electric water heater, modified to run on 12V. An idea covered by BoyWonder, about halfway down this thread
I initially considered putting a standard plastic water tank in the cabinet over the wheel well on the passenger side. This would be right next to the sink, and I could fit an 18-20 gallon tank. The problem is the tank would be installed above the wheel well. This put the tank pretty high in the van and the fill port would be pretty high up on the outside of the van. Also I could not find a good way to run the fill port to the outside wall of the van. I was also not too keen on cutting another hole hole in the van.
I decided to do something similar to what was done in this video
I purchased four 5-gallon jugs for a total water capacity of 20 gallons. There were heavy duty, military grade jugs. There will be 10 gallons connected to the water pump at any one time, but I have a location to store two more full jugs. I liked the flexibility of being able to easily vary the amount of water we carry. I also like the flexibility on how to fill the jugs. They can be filled anywhere we can get fresh water. When we are at a campground, I can just carry the jugs to a spigot and fill them up, no need to move the van. They will also be easy to clean and dry for storage.
I will have two of the 5 gallon jugs strapped down under the sink. I cut off the pour port off the lid and replaced the port with a quick-connect coupler thats connected to a tube that goes to the bottom of the jug. These fitting have built in check valves that keep the water in the tubing when they are disconnected. This keeps the water from spilling from the tubing when they are disconnected. It will also keep the pump primed. The other half of the quick-connect is connected to a short piece of tubing, with the other end of the tubing connected to a barbed tee fitting.
The output of the tee fitting runs from the jugs to a strainer and the water pump. On the pressure side of the pump I switched to a higher pressure tubing that goes from the pump to the hot water heater and cold water side of the tap. Another hose is connected the hot water heater to provide water to the hot side of the tap.
I really like the idea of electric hot water. I designed the system to either use excessive solar power, after the batteries are charged, or just powered directly from the batteries. The main control for the system is through a double pole, 3 position switch. The three switch positions are Solar, OFF, Battery. When the switch is set for Solar, the Victron battery monitoring system (BMV712) uses an internal relay that can be energized based on the state of charge (SOC) of the battery. Currently I have it set to close the relay when the SOC is between 95-100%. When the relay is closed, it energizes a second external 30/40 amp relay that will complete the connection between the battery and the 12V heating element. When the SOC is below 95%, the BMS relay opens and de-energizes the system. When I leave on a trip, I will set the switch to Solar and the water will be heated whenever the battery charge is above 95%. If I need hot water when the battery SOC is below 95%, I move the switch to Battery. This will energize the 30/40 amp relay and heat the water regardless of the battery SOC. The OFF position will not allow the amp relay to get any signal, keeping the heating element de-energized.
The description above may be difficult to follow, so the sketch below may help.
The hot water heater is similar to what Boywonder did in this thread: http://www.sportsmobileforum.com/for...ter-13704.html
. I used the 2.5 gallon hot water heater from Home Depot and a 12V, 300W element from Missouri Solar. The 300W element is a little shorter than the stock element, but fits fine in the same hole. I replaced the 120V cord with the 8 ga wire from the battery (through a 40 amp circuit breaker) and wired the positive to the upper part of the thermostat and the negative to the second terminal of the 12V heating element. I replaced the door and also wrapped the hot water heater with a blanket of insulation.
I used a couple of wood brackets with long hose clamps to hold the hot water heater in place.
I still need to plumb a discharge hose for the pressure relief valve. To drain the water heater in the winter, I will attach a hose to the drain valve and run it out the door.
My first test of the system was successful. No scientific test, but I parked the van in the sun, flipped the switch to solar and went in to eat lunch. The batteries were fully charged so the 12V heating element was immediately energized. After about 40 minutes I tested the temperature and the water was very hot. I left the heater on for another hour and then turned it off. The water stayed hot through the evening and was still fairly warm the next morning (16-18 hours later). I tested the water temperature a few times in this time period, but did not run much cold water into the heater. And it was a hot sunny day, obviously I will get different results when the outside temperature is lower.
For a real world test, we did a 3 night trip into the mountains of northern Utah. The hot water heater was only powered by the excessive solar power. We essentially always had hot water. During the day the battery SOC was always around 98-100% so the water was heated and maintained hot. By bedtime, the battery had dropped to ~70% as we used the microwave or induction cook top to cook our dinner. The water was still hot in the morning and by 9 am the battery was back to 100% and heating the water again. We only used the water for washing hands and dishes, so we did not consume a lot of hot water.
Overall, I a real happy with the water system and hot water heater. It was relatively cheap ($250-$300), compact and pretty easy to install. It was nice not to have to worry about installing and maintaining a propane system. Filling the water is not as easy as a large permanent tank, if a hose with potable water is available. But I like the flexibility of the smaller water jugs. After our trip I dumped the jugs and dried the inside of them with a towel. This will keep things a lot cleaner.
FYI, I have 400 watts of solar, feeding two 100 amp-hour lithium batteries. It would be enough to keep us in hot water when the sun is shining.
For our trip we ran the sink drain into an empty water jug used a temporary gray water tank. The next project is installing a gray water tank under the van.
I also finished the sliding doors for the electrical cabinet and closet.