Water System Questions f(r)om Dummies

[JMacs]

I am reposting this from the Expedition Trailers section. Only got one reply. While helpful, they weren't able to answer all of my questions.

So I found a trailer on Craigslist that is cheap enough that I think I can finally start my build. The idea is a small, dedicated trailer to carry all of our camping and kitchen stuff. I want to include a sink in the kitchen area, but I have some questions.

I am planning on installing a Shurflo Revolution pump. The way I understand it. You have a switch that turns the pump on. It runs constantly pressurizing the water at the tap. It has its own internal pressure bypass that allows it to keep running without either burning up or over-pressurizing the system. When you are done, you switch the power off. Correct? How long can you leave the pump on without burning it up?

The plan has the water tanks installed under the bed of the trailer. Create a metal support and metal tray. Try and make it easily removeable or accessible from above if I ever need to get at the tanks. Question for those of you who have done it. How did you handle the drain line? In most of the diagrams I have seen, there has been a drain valve to completely empty the tank. Did you just stick it out the side? Or did you install it at all? Is there something you would have done differently if you were going to do it again?

And yes, there will be 2 tanks. One for cold and one for hot. I want to install a drain-back solar hot water heating system. There are some really simple ideas out there that I have seen that involve making a shallow box with a clear top, 60’ of coiled copper water pipe, and some black paint. (of course, I can’t find the pictures on the web right now.) Install a diverter valve from the water pump and circulate it up to the roof of the trailer. Ta-da. Hot water. Only downside is that I will have to either make sure the solar collector is really well drained in winter, or make it removeable.

The last question. What do you do with the gray water coming from the sink? Drain it onto the ground? Collect it in a buck and the go pour it out in the grass?

 

[dwh]

The pump has an internal bypass so it doesn't load up when the valve is partially open. Say a 3gpm pump, but the valve is only open enough to allow 1gpm.

It also has a pressure switch that turns it off at 55psi. So if you close the valve, it'll run another second or so until the system pressure hits 55psi and then turn itself off. Once you open the valve again, pressure drops and the pump turns on.

The only reason you need to add a switch at all is to turn it off when you don't need it so that if a leak develops it doesn't pump out all your water, or in case the tank is empty, the pump doesn't just sit there running continuously till the battery is dead.

Otherwise, you could just wire it direct and forget about it, won't hurt the pump to have power available 24/7.

 

[dwh]

Solar water heating usually requires continuously circulating the water from the the hot tank up to the solar collector and back again. Over a few hours (or days) the water in the tank gradually heats up.

Going from your cold tank, up to the collector and back down to the hot tank one time only, probably won't get you much heat.

So you'd have to put water in the hot tank, and rig the pump to draw from the hot tank, and then return from the collector to the hot tank.

So two separate water systems with valves to switch the pump between them.

Okay fine, but what if you want hot and cold water mixed at the tap?


Another issue, is pump volume. Solar collectors tend to use low-volume pumps so the water spends time moving through the collector slowly to absorb the most heat. Would a 3gpm pump move the water through the collector too fast?



(Edit: D'oh! Forgot to add the punchline.)

So you'd probably be better off with two pumps. One to pull from the hot and cold tanks to feed the mixing valve at the sink, and another small, low volume, low amp draw pump to run for hours to circulate the hot water through the solar collector.

 

[dwh]

About needing a drain valve on the water tank.

If you've gotta drain the solar collector in the winter, you'll have to drain the water tank too.

You could just use the pump and pump it out, but water systems need periodic cleaning.

It's pretty easy to just open the drain valve and stick a hose in and turn it on and let it run a while to flush the tank.

When I do it on my campervan, I turn the pump on too and flush all the lines at the same time the tank is being flushed.

Up to you either way.

 

[dwh]

My truck has a grey water tank, but back in my jeep/tent days grey went into a bucket then poured over the campfire or near the roots of a tree.

Ya don't want that stuff underfoot in your camp.

 

[JMacs]

So it just goes to show that you just have to ask the right people. Thanks for all the information!!

My idea was to pump water from the hot water tank up to the collector and just slowly heat up the water that way. There is a video of a guy using this type of system and 1/4" copper and getting 165 degree water out at about 1 gpm. (It is on the internet so it has to be true!) I was going to go with a larger copper pipe to more closely match the pump. I wasn't sure if restricting the pump for a longer time would cause some issues. Worst case, the water makes a couple of cycles through the collector to get up to temp.

And yes, I was going to have 2 pumps and a hot/cold faucet at the sink.

This is going to be quite a step up from my current 1 gallon milk jugs and a plastic tub. Which gets poured on the ground as far away from camp as reasonable. Just in case there is something in the water that the ants might like.