DIY Solar Hot Water

[MadTripper]

I've been looking around for some ideas to tie solar into my radiant heat. I started looking at car radiators as a collector which I hope to experiment with shortly but I did find this use for an old refrigerator coil which was pretty interesting.

http://www.instructables.com/id/Solar-Thermal-Water-Heater-For-Less-Than-Five-Doll/

The tubes are a little small for thermosiphon to take place on the level needed however if you were to introduce a zone pump, this would be a decent start. I also wonder if you could improve by adding 3 or 4 coils in the same arrangment but offset.

Tripper

[johnjmw]

Tripper,
I'd think as long as they didn't shade each other using 3-4 would be an improvement. Most of the home brew I use to read about were made with flexible 3/8 or 1/2 copper tubing either sprayed black for heat absorption or plastered into a thin coating of ??plaster/mud/clay?? and to distribute the heat evenly to the pipes. I thought the winding was about a 2" space between horizontal passes on a 4'x8' backing which was boxed and insulated. Once I get my cabin built I'll be trying a few different styles for domestic hot and heating during the winter.
My question is what do you do with that big a collector during the summer so it doesn't over heat? Take it down? Cover it? I'd hate to boil out the liquid every summer while I don't need the extra heat.
John

[MadTripper]

I figured if you positioned the panel right, as the sun climbed the sky in the summer, it would not be a direct shot. Also by adding an overhang of sorts would help. I plan on using an old 40 gallon water heater as a storage tank. I also heat my domestic hot water with an indirect tank which acts as a 3rd zone for my heating system. It would be pretty easy to set up a control system that would circulate the water when it gets to be a certain temperature. Of course all adding to the complexity would in turn increase efficiency, but items like auto fill valves and pressure/temp relief valves are pretty necessary. I'll try and come up with a diagram for what I'm thinking and post back. Perhaps even simpler would be a shade that rolls down over your collector either during portions of the year or if you are away from the house.

Tripper

[johnjmw]

I know what you mean. Except I like to try to KISS (Keep It Simple Stupid) to many gadgets and there is also more to go wrong. I'll be setting it up probably with as large of a used electric hot water tank as I can find. Then replace the heating element with a DC element and feed any excess power through it also. Which if I ever get to the point of putting the Wind genny up I should have plenty. Plus I'll have a small electric DHW tank next to the regular one which will be having the same style DC element for us to use too.

John

[paleosmith]

Hey Y'all,

Im new here. This will be my first post here so let me give a little background: I have tinkered with this for years but have never had the chance to get as full blown Off the Grid as I would like. We are now buying a house and I want out of the loop something fierce.

Having said that, could one of you either post some pics or give a decent description of your systems? It's funny that you posted the $5 tutorial because I saw that just yesterday and have already started my plans for expanding it (My plan is to offset multiple coils, which have been painted or coated flat black, with a reflective copper plate backgrond that will be dished to focus the reflected light).

But, because of my limitied experience, I am unsure how I want to tie this in to the On Grid HWH. My thought is to have a large tank in line before the On Grid tank with a timed circulation pump (12V of course) to heat the pre-tank. Is this what you folks are doing?

Also, I have figured I could build a bank or old auto heater cores (about the size of a large HWH) divert some of the heat to that and use it help heat the house. I have the same problem of how to tie it in. I was thinking a separate thermostat and 12V fan to slowly heat the house thereby lightening the load (I also will be using wood for the bulk of the heat). Some help with these two ideas would be great and look for a similarly long posts about biodiesel generators, wind, and battery banks.

Thanks in advance,
Rob

[MadTripper]

Interesting. I haven't moved on my setup yet but I have been collecting parts. I picked up a radiator from a wreck, I have a like new natural gas 50 gallon DHW, and I just picked up a set of french doors that were pulled.

So, I was going to build a space heater off of my existing propane boiler using the radiator and fan. That is more of a safety item for our downstairs although I don't think we'll need it.

I plan on making a coil system like you are talking about and use the french doors (actually the window portions) in a frame. They are exterior windows so they are insulated and double pane.

I thought I'd use the heater as a storage tank. I would have to build a heat exchange of some sort but my well water would enter the storage tank prior to my current DHW. Even if the solar wasn't pumping, I would place it close enough to my wood stove so that it would preheat which would take a little load off of my indirect system.

Sorry I can't provide pictures but I'm not real concrete on my plans. I contemplated using a straight up heat exchange like you would find on an external woodstove app for making dhw. The issue would be what to do with the heat when I'm not calling for dhw. Anyways, if you come up with something or start construction, pass the info on.

Tripper