CAROLYN'S BLOG ABOUT THE HOUSE CONSTRUCTION
AND THE YEARS BEYOND
(back to blog index)

Sun, Mar 13
6:30 am

Building Your Own Solar Water Heater: I love things that are easy to make, inexpensive and they do the job of complex, expensive systems! Such is the case with this handmade solar water heater. By the end of the house construction, I was totally out of money, but I really wanted to use all this wonderful Southwest sunshine to heat my water. Jon Ruez, my consultant and friend, knew how to make this water heater and it cost almost nothing. It still stands today, ten years later, and does an amazing job. All you need is sun.

Basically, we put a solar oven around a hot water tank. I decided not to put it on my roof, because I get plenty of sun down on the ground and it would be very heavy. I couldn't see why I would want to build supports onto the roof, run the plumbing way up there and then risk the whole thing leaking on top of my roof. So, I put it on the ground, facing south, right above where the plumbing runs underground to the house.

First, Jon got an old hot water heater tank from a plumber friend of his. It was full of mineral deposits, but we took it outside, removed the outer casing and blasted a hose through the tank to wash out all the deposits. When it was clean and dry, we painted the outside black.

Part of the issue, it seemed to me, was keeping the water hot overnight, because I like to take morning showers before I go to work. So, since weight was not an issue, we made a base for the water tank with a couple straw bales that would also be used for insulation. As always, to keep the bales dry, we put them up on some concrete CMU block. These blocks have holes in them to let any water drain down. We also put the heater up on a little slope, so water would run around it. Then we bought some foil-covered boards.

Here is the cleaned water tank, painted black, on its straw bale and reflective base. It is facing south, of course, out of the shadow of bushes and trees, so it gets as much sun as possible.

Cost so far is maybe about $10 - I can't remember where we got those foil boards exactly or what they cost. I think we got them at a home improvement center. Or maybe we made them from leftover radiant heat barrier foil. You could use those wonderful, inexpensive emergency blankets, also, I would think.

Then, we plumbed connectors from water pipe below ground up and into the hot water heater. We had to have one water pipe that continued to the house and became cold water, in addition to the pipe that went up and into the hot water heater. We used the same inflow and outflow connections that any hot water heater has. The outflow valve, where the hot water leaves the tank, should be the highest one. As does hot air, hot water rises, so you want to siphon the hottest water out from the top of the tank. Also, Jon attached a release valve, so if the water boiled, the steam would have a vent. That's important when we get over 100 degrees in the summer.

When all these connections were made, we built a wooden triangular frame around the heater, with holes for all the pipes. We got an old sliding glass door panel from a recycle store; a double-pane one to help keep the heat in and faced it south. I stuccoed the whole thing to keep the bales dry and even roofed it with a little leftover roofing. I wouldn't use earthen plasters on something that is very exposed to the elements. I made a hinged cover of more foil board that I could put up in the night to keep the water warm for the morning.

For a year or so, I had this hot water heater feeding into the pipes that then flowed into my regular hot water heater. The problem was that I had no way of telling how much work this solar heater was dong, because I had the electric tank to boost the water. So, after my kids left home, I gave away my electric hot water tank and had the water from this heater go directly into the house. It worked amazingly well in the hot summer (joke) but cold water is the problem in our summers. I found that sometimes when I wanted hot water the most was during cold winter storms. Those storms were often cloudy and I was taking lukewarm showers on these cold mornings. (a real waker-upper, by the way - better than Starbucks!)

So, a couple years ago, I bought a small tankless water heater to be able to give this solar water a boost when needed. I didn't buy the whole-house $1000 kind, just the $200 single-faucet kind, because I only need hot water one faucet at a time. It has done an amazing job. When I removed my hot water heater, I saw my electric bill go down about $5 to $10 per month - and it would be more at today's rates. When I added my tankless, I did not see my electric bill go back up. It goes on for only a very short time when cool or lukewarm water is running through its coils. If the water coming into the tankless is hot enough, it doesn't go on at all. I highly recommend this system for saving energy!

Keep it Simple - and be kind!
Carolyn