Built in solar water heater/shower.

[ZOFCHAK]

I'm currently considering building a 5 to 10 gallon insulated aluminum tank in my cargo trailer and using a very small 12v pump to slowly recirculate the water through solar panels on the roof. I'm also going to add a small hand pump to the tank so that I can pressurize the water to the shower head as needed. Perhaps I may even wire the pump to a switch so that when the water reached a predetermined temp it would turn off the pump and leave the heated water in the tank.

The panels I'm looking at are the SW-38 panels which seem to get fairly good reviews and are compact enough to easily fit on the trailer. I'm guessing that 2 of them would be enough for the job.

http://www.amazon.com/SW-38-Solar-Water-Heater-Panels/dp/B0041VM58E

Anyone here have or seen a similar setup? Can any think of any issues or problems that I may encounter with these panels? Anyone have these particular panels?

 

[Van-Tramp]

I have heard of people simply running black PVC pipe, back and forth numerous times, on the roof of their {whatever} and filling that with water. Then a simple hose and nozzle at one end gives you a gravity fed shower with some hot water. I haven't tried it myself, but I have tried the basic 5-gallon solar shower and it works great. Others have give a simple 5 gallon bucket painted black good reviews too, so I see no reason the PVC piping would do any worse.

A couple dozen feet of PVC and the couplers will run you much less than a single one of those solar panels. Worth a try first if you are frugal like me.

 

[stude53]

Here is the link to the Solar hot water build from the dropdown tabs along the top of this forum, a wealth of information.

http://www.cheaprvliving.com/solar-hot-water-electricity/

Bob

 

[ZOFCHAK]

Thanks for the replies and the links.

I considered a roof top gravity setup similar to the one in the link, but there were a couple negatives to those designs that I wanted to avoid. The first being that it's not insulated so one would be limited by the time of day to access the heated water. I'd like to have the ability to have warm water in the morning hours, so I figure the only way to do that would be to have a system that stored the water in an insulated tank after it was heated. The second part I did not like was the volume of equipment on the roof. For both gas mileage and stealth reasons I prefer to keep as little visible from the outside as possible. The third reason is that it would be difficult for me to fill a gravity fed system without a pump as the one in the link has. With the insulated tank being on the floor of my trailer I can easily fill it and can add cool or hot water to it if I need to adjust the temp for bathing.

 

[WheelEstate USA]

I built a couple of solar water heaters out of ABS (black) field piping on a remote property I used to have. It lasts longer in the sun than even painted PVC, which becomes brittle with sun and extreme heat.
Heated water went to an insulated mixing tank. A cheapo 12V pump provided water pressure. I regulated temps using a standard mixing faucet.
Worked great and would produce scalding hot water in a short time.

In the van, I find the solar shower bag to be the easiest, cheapest way to have hot water. Even after sundown, water stays pretty warm for quite a while, especially if wrapped in a towel in the front floorboard.
I thought about getting one of those flexible, foldable insulated bags to slip the hot shower bag into at night, but haven't found it necessary to do so.
The insulated bag might be nice in the winter so there will be warm water to wash up with on cool mornings tho.

A solar shower bag at WalMart is about 12-15 bucks and we're on year 3 with ours. Good investment, cheap and easy in my book.
(used it more than we did the water heater in the RV)

 

[LeeRevell]

For my van camper conversion, I am planning to use one of those hand pump garden sprayer jugs, with a shower head in the hose. Seen it in some youtube videos - looks very workable. Leaving it in the hot sun should heat it nicely, then wrap it in something to help maintain the heat.

 

[SoulRaven]

Masonry sprayers come painted black and if you cut the wand down to a couple of inches the trigger sprayer nozzle will have an adjustable spray pattern.

 

[akrvbob]

I don't understand the concept of running tubing through a solar panel. If the tubing is one top it blocks the sun and no more power generated. If it is underneath it's in the shade and it won't warm up. Can you give us more details?

I think you may be overestimating the amount of stuff on the roof for my friends system. It's just 2 inch PVC tubing going back and forth. If it were me I would put it on a sheet or plywood hung between two ladder racks. Put some 2x2 across the sides and throw a step ladder up there they would be invisible and actually increase your stealth.

Adding your insulated water tank to my friends system would be very easy and might solve the morning hot water problem.

Bear in mind, this will all work great in the summer almost no matter how you do it, but in the winter it will barely work at all. My friend experimented with buiding a box around his tubing and putting a piece of Lexan on top. It got very hot, very fast even on Dec 21st!! So hot it burst his joints! He tried to build in vents and regulate the heat but it turned into a big job and was going to need nearly constant attention to keep the heat down in the winter. And then you have the constant transition from winter to spring to summer and constant need to adjust to keep the temperatues down to reasonable level.

He was older and getting on the roof was difficult for him so he just gave up on winter solar hot water.
Bob

 

[ZOFCHAK]

Bob, The "Solar Panels" I was thinking of using aren't the electric type, they're basically a commercial built system similar to what you described above, but use much smaller line than 2" PVC. They are encased with glass/Lexan as well so that they heat up from the sun, but don't lose heat to the surrounding air as quickly.

 

[Patrick46]

So, you're thinking of heating the water on Monday afternoon for your Tuesday morning shower?? Did I get this right??

The problem I see is not heating the water...it's KEEPING it hot until the next morning. Even using some sort of super insulated water tank...I can't see anything keeping it HOT throughout the entire night. It's gonna be luke-warm by morning at best...unless you have a way of keeping it heated durring the night, or reheating it in the am. (which I think we're trying to divert here.)

correct me if I'm wrong.

 

[ZOFCHAK]

So, you're thinking of heating the water on Monday afternoon for your Tuesday morning shower?? Did I get this right??

The problem I see is not heating the water...it's KEEPING it hot until the next morning. Even using some sort of super insulated water tank...I can't see anything keeping it HOT throughout the entire night. It's gonna be luke-warm by morning at best...unless you have a way of keeping it heated durring the night, or reheating it in the am. (which I think we're trying to divert here.)

correct me if I'm wrong.

I don't expect it to be hot, but warm sure beats cold! I do have a Triton outdoor propane shower that works well when needed. I could use that in combination with the solar panel and tank and would use a whole lot less propane not having the heat the water up from a low starting point.

 

[Rey8]

Hmmm, what if you made a water tank out of one of those insulated 7 day coolers? They are supposed to keep things frozen a long time, maybe they would keep some water warm too for a couple of days?

 

[ZOFCHAK]

I think a cooler would probably work okay as long as the water didn't get so hot that it affected the plastic. I would not be able to pressurize it, but could use a 12v pump for the shower which would probably make for a simpler setup anyhow.

 

[WheelEstate USA]

The 6 gal water heater in the RV would still be plenty warm in the morning for bathing after bring off all night.
A 3 gal Igloo water jug might work, especially if wrapped with Reflectix....which, btw, has extended ice life in my chest from 2 days to 4 on a single 10# bag. Hummm....I think a YT vid is blooming here

 

[Bdog1]

A few years back I made a solar heater from an enclosed box with a glass face housing 100' of 3/8" black plastic tubing, randomly arranged. The water was circulated by a 12v pump, that ran off a solar panel. ( No sun, no pump. Night time, no pump). This heated a hot tub surprisingly well!

Seems a similar system could be made vehicle friendly. The more water heated the longer it will hold it's heat. It's not like you really need to store hot and cold water, just a combined warm tank would work. Right?

 

[Geodoc]

I did an experiment with a 5 gallon bucket lined with Reflectix, and here are the results:

2:00 PM - put four 2 liter bottles filled with water in bucket - water temp was 110F.

6:00 AM the next morning (14 hours later) - water temp was 84F.

If you put the hot water in later (e.g., 5 or 6 PM) and it's hotter than 110F, you should still have some nice warm water early the next morning.

I would recommend having some black PVC pipe, enough to hold 2-4 gallons, and then drain it and store it in a reflectix lined vessel (remember, more concentrated mass loses heat at a slower rate), and find a way to use it as a shower in the morning (I personally recommend the Simple Shower )

 

[akrvbob]

I had a friend who did something similiar but low tech. She painted some 1 gallon water bottles black and left them in the sun surrounded by Reflectix to aim the sun at the bottles. Even in the winter they would hit 140 degrees F on a clear day.

At the same time she took a cooler and left it opened and pointed at the sun so it got hot into the insulation. At the end of the day she wrapped the water bottles in a blanket and put them in the cooler and took them in her van. She said she always had warm water left in the morning.

That would have worked much better if she had painted the inside of the oven black to absorb more heat.

Basically we're talking about haybox cooking but instead of cooking food we're keeping wash water warm over night. That's proven to work and only requires enough insulation.

I think you have a great and practical idea! My only word of warning based on my friends experience is that the water will get VERY hot and will have VERY high pressures--think of a pressure cooker instead of a haybox cooker. So be sure to use plumbing techniques designed for high pressures. The plumbing in his Class C couldn't handle them.
Bob

 

[Neptune]

I did an experiment with a 5 gallon bucket lined with Reflectix, and here are the results:

2:00 PM - put four 2 liter bottles filled with water in bucket - water temp was 110F.

6:00 AM the next morning (14 hours later) - water temp was 84F.

If you put the hot water in later (e.g., 5 or 6 PM) and it's hotter than 110F, you should still have some nice warm water early the next morning.

I would recommend having some black PVC pipe, enough to hold 2-4 gallons, and then drain it and store it in a reflectix lined vessel (remember, more concentrated mass loses heat at a slower rate), and find a way to use it as a shower in the morning (I personally recommend the Simple Shower )

Was the ambient temp 84 degrees too? Without other information, your experiment is, unfortunately, meaningless. 6 months from now your experiment might leave you with 34 degree water at 6 am.

Oh, and there are formulas for calculating heat absorption and dissipation of water at varying temperatures. Scientists figured this out long ago.

 

[Geodoc]

I had a friend who did something similiar but low tech. She painted some 1 gallon water bottles black and left them in the sun surrounded by Reflectix to aim the sun at the bottles. Even in the winter they would hit 140 degrees F on a clear day.

At the same time she took a cooler and left it opened and pointed at the sun so it got hot into the insulation. At the end of the day she wrapped the water bottles in a blanket and put them in the cooler and took them in her van. She said she always had warm water left in the morning.

Bob, I remember reading one of your articles on that, which is how I came to develop my Simple Shower. I looked at that picture and asked "why not put a shower head on that?". Three years later, we're in production (and on Amazon).

---

Was the ambient temp 84 degrees too? Without other information, your experiment is, unfortunately, meaningless. 6 months from now your experiment might leave you with 34 degree water at 6 am.

Oh, and there are formulas for calculating heat absorption and dissipation of water at varying temperatures. Scientists figured this out long ago.

Ambient temp was 61F at the time of final check. It had been 67F until 10:00 PM when I turned the heat in the house off.

Not being the type of scientist who knows about thermodynamics, I went with a real life test

 

[Neptune]

Ambient temp was 61F at the time of final check. It had been 67F until 10:00 PM when I turned the heat in the house off.

Not being the type of scientist who knows about thermodynamics, I went with a real life test

I respect you getting out there and testing it yourself! Sounds like a good start! Keep it up!