Solar water heater for the bathroom

[Erik_L]

Per our discussion with Gay last night, and the post meeting discussion with Kris and Rick I would like to start a thread for the planning and execution of this project.

Our project goals so far are:
3-10 gallon capacity, basically enough water for hand washing.
Low power consumption, it would be nice to be able to power the system off a 20 watt solar panel
Some system and mechanical logic to prevent the system from freezing, burning people with hot water, etc.

Kris, you were trying to run estimates on how much water we could hold in a 3'x3' solar collector, if you get that figure please post that here.

Ideally we would like to build the collector ourselves to save the bulk of the cost, I am not opposed to buying the control systems off the shelf if needed. I will start doing some research and post links as diagrams as relevant.

[Erik_L]

http://www.instructables.com/id/Cheap-solar-heater/

http://www.instructables.com/id/Homemad ... ation-wit/

http://www.instructables.com/id/Solar-W ... Collector/

[Erik_L]

I am thinking a tank like this, and then stuffing it inside a wooden box with insulation like we discussed last night.
http://www.amazon.com/Gallon-Fresh-Wate ... B007MSDYFQ

Here is an idea for a pump:
http://www.en.misolarcasero.com/my-solar-water-pump/
This pump uses 1 amp at 12 volts, so a 20 watt panel charging a 12 Ah SLA (have some kicking around my apt.) would be able to run this no problem.

[brownk607]

I posted this on the wiki.
http://tcmakerspace.com/wiki/index.php? ... ter_Heater
Here is a screenshot I was able to grab when LibreCAD crashed on me before I could save. I'll redraw it again in AutoCAD when I can get around to it.
http://tcmakerspace.com/wiki/images/6/6 ... Heater.png
~0.68 Gallons in about 67 LF of 0.5" diameter pipe (23, 2'-10" long sections + 2' additional).

[Erik_L]

CAD render looks great, and I like the wiki entry

I've been doing a little research and I really like this guys build.
http://www.builditsolar.com/Projects/Wa ... orTest.htm
http://www.youtube.com/watch?v=WP8H5IOTwYU

Here is the pump he uses which is a low power consumption pump, using 1.25 amps at 12 volts DC.
http://www.amazon.com/Solar-Circulation ... B005EU7ONM

Main thing I like about this build is that it uses CPVC which is cheap and easy to work with. I think it might be a good starting point to build a small low cost unit that we can experiment with and see if we can get the water hot enough to be usable (I really doubt that we won't be able to).
One problem that we might have with using CPVC though is that it can start melting at above 200F, so we might need to give the system a way to suck in new (cooler) water if starts getting too hot, or install a fan with a servo controlled flap so it can vent the heat collection chamber and thus reduce it's internal temperature. This doesn't seem like it would be to hard to do (servo actuation) and is a task I am going to have to undertake anyway on the solar pop can heater project, as I would like to have that system be able to close it's vents when it detects the air inside the space is warmer than the air that it's producing (night time).