I have been into making my home more "green" for some time now. Not so much for the enviroment but actually for my wallet. I heat with a wood/coal boiler that heats my house for about $250 a year and I am also planning right now to power my whole home with micro hydro power ( no more electric bill !! )
I heat my domestic water with my boiler but in the summer my boiler isn't fired. So, I was looking into the solar water heaters for the summer.
Anyone have one? if so, can you add a link?

 

I have one that I designed and built. I leave my water heater off for about six months a year and for about three more months it does most of the water heating. The rest, Dec through Feb, I get maybe 10%-25% or so.

One of the most important considerations when thinking about solar hot water is designing the freeze protection system. Decide on that first and consider all failure modes to make sure it will always be safe. Then size the system for your needs.

In the long run the best system will either drain the panels to a separate small holding tank when not in use and deliver the energy through a heat exchanger or use a propylene glycol solution in the panels and a heat exchanger. Be sure you use all copper, glass glazed collectors. And spend your money on flat plate collectors, not on fancy tracking equipment or evacuated tube hype.

When you've picked the number and size of collectors you want (for instance two 4X8s) then pick your storage size, probably 120 gallons for those collectors. Next, design the system to "cool" the collectors, not to heat the water. The best efficiency comes from keeping the panels as cool as your system can. That means a good circulation rate with a small temp rise per pass through the collector.

Be sure to use a differential controller with sensors and not just a timer to run the system.

If you insist on absolute simplicity and no power draw you could go with a simple batch system. Lower efficiency per collection area, but no electricity. Just be aware of it's freeze protection system and wether it makes sense to you.

With these few basics you can end up with a system you'll be very happy with for years


John

 

raspy would you still feel the same about the vacuum tube water heaters up here just outside of cloudy portland.

 

Yes I would unless you could demonstrate that they will actually collect more BTUs per dollar and will last longer.

Vacuum tubes are good for high temps, but that is not what DHW systems need.

In marginal areas a good quality insulated collector with low E glass and a black chrome selective surface will do just fine. No matter how you slice it aperture area and a temperature in the normal DHW working range are what we need. Other factors are simplicity, easy maintenance and foolproof freeze protection. Then consider a collector design that is mass produced by competing interests, not some proprietary design that costs way more for the same performance and from someone who may be out of business next year. If that happens and a baseball breaks the glass what do you do?

Finally, don't be fooled by high temperature claims (unless you want to run a steam turbine). It's BTUs we're after, not high temps.


John

 

Not our water heater, but our pool is solar heated. It is still hovering right near 80* in the middle of January. It certainly works!!

 

I have one I put together myself. 120 gallon storage tank. Circ pump operates on a thermostat. Two roof panels. Works marvelous. Of course, I live in Florida. I had to run the electric on it two days last year.

 

Home Power magazine is one of the best sources if info , you can buy back issues mags or CDs .

http://www.homepower.com/

 

thanks for the reply , it will give me something to think about it will be a couple years before i get any installed. new house on the farm is my first job. well insulated with radiant floor heat.

 

I'd love to learn more about this stuff ...

Will these solar collectors keep up with a family that enjoys long, hot showers ?? What kind of $$ are we talking about to get set up with this ?

PISTOL

 

If you can make your own stuff , its real cheap .
If not then finding someone that is all about less consumption then it cost what its worth .
Watch out for the high tech systems , they can get costly enough to make it hard to justify .
While were at it do not forget geothermal , 2 types one just goes in ground and bring temp up so that what ever other kind of water heater you have only needs to raise temp [ or lower , for cooling ] half as much .
Then if your close to hot ground , like NO. California , Yellow Stone ect. , hot springs .
As for long showers , it just has to be engineered for what you want , want more = cost more .
The Home Power link above is a huge source of info [ mainly do it yourselfers ] , and contacts , supplies .
This is where its obvious that its hidden tech , energy crisis for how many decades , and this is one of 2 magazines out there .

 

here is some info I have found, plan on doing it this year. Just have to aquire my old hot water heaters.....for free hopefully...and legally.

http://www.motherearthnews.com/DIY/1...er-Heater.aspx
http://www.builditsolar.com/Projects...er_heating.htm

One of these is real good with lots of info as far a positioning of your "rig". I believe it was due south or 20 degrees either way. Also a neat trick on figuring what shadows would interfere with your heater. The trick depends on your location....latitude and longitude.

You can use your existing water pressure, as I have city water...live out in the sticks but they managed to run a line along our road. Anyhow, you can pipe in to your water line coming in and have it feed your batch heaters giving you the pressure to flow the water. After that I will flow the hot water to my current hot water heater for additional storage before it is needed. Two 120 gallon tanks..I hope, due south view on the side of a ridge with no shadows to worry about. Insulating your box, watch what you use cause it will get hot inside. The insulation will melt and I saw a picture that showed a 180 degree thermometer melted.

Real cool stuff and I'm doing it for the same reason, easier on my wallet, plus I believe there is a tax credit, some $750 so I plan on keeping mine as close to that as possible, lots of homemade stuff.

Shawn