The goal: Build a passive solar water heater to make the frigid water in the public bathroom less shocking to the human body. It needs to be a closed loop system because it freezes where we are a few times a year. Having water run through the collector will freeze the sitting water in the winter month nights and apparently scald hands in the summer months.
The background: We know a solar water heater can be made, but making it work everyday without requiring constant adjustment and fiddling is the tricky part. I'm lucky, my mother owns a hardware store (awesome place to grow up) and she decided to fund the project. She let me build it at the store and agreed to deal with the ridiculous time line I often fall into on pet projects like this. This will be installed to provide warmer than ice cold water to the hardware store bathroom and will only really be used for washing hands and cleaning etc...
I've broken the project into three phases:
1- The Collector: A heat exchanger that will collect the sun heat energy and efficiently transfer it to whatever fluid media we end up using to carry the heat to our desired location.
2- The Emitter: Yet another heat exchanger that will deliver the heat from my carry fluid to the water the end user will come into contact with.
3- The Install: making it all work as maintenance free as possible... probably the hardest part.
This 'ible covers Phase 1. I will not be as long winded in the steps as I was here.
The background: We know a solar water heater can be made, but making it work everyday without requiring constant adjustment and fiddling is the tricky part. I'm lucky, my mother owns a hardware store (awesome place to grow up) and she decided to fund the project. She let me build it at the store and agreed to deal with the ridiculous time line I often fall into on pet projects like this. This will be installed to provide warmer than ice cold water to the hardware store bathroom and will only really be used for washing hands and cleaning etc...
I've broken the project into three phases:
1- The Collector: A heat exchanger that will collect the sun heat energy and efficiently transfer it to whatever fluid media we end up using to carry the heat to our desired location.
2- The Emitter: Yet another heat exchanger that will deliver the heat from my carry fluid to the water the end user will come into contact with.
3- The Install: making it all work as maintenance free as possible... probably the hardest part.
This 'ible covers Phase 1. I will not be as long winded in the steps as I was here.
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Signing UpStep 1: The Box
I found an old table that had been partially disassembled and re-purposed it for my box. I'm not much of a carpenter, but the box serves it purpose well. The final picture in this step is showing the black silicon I used to seal the inner joints of the box all the way around. I wanted to have a relatively air box when I was done.
A picture speaks a 1000 words, so I'm not going to step by step the box construction. I've opted not to go into great detail about quantities and sizes because I think those metrics would be governed by the specific application. There is so much to say about each picture that this 'ible could end up being a royal pain to read; so I'll keep it nice and general for the sake of easy reading. Hopefully the photos do the talking.
A picture speaks a 1000 words, so I'm not going to step by step the box construction. I've opted not to go into great detail about quantities and sizes because I think those metrics would be governed by the specific application. There is so much to say about each picture that this 'ible could end up being a royal pain to read; so I'll keep it nice and general for the sake of easy reading. Hopefully the photos do the talking.
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One quick question tho: wouldn't it be more effective to connect inlet of the collector with an outlet at the bottom of bucket and outlet of collector in the top of bucket? this way, when rising the bucket a little higher than the collector, natural circulation should do the work. And also, due to the fact that you would take the cold(er) water from the bottom of the bucket to be heated, it should prevent the problem with the vapor lock (well, at least til the whole bucketfull is boiling :) ?
Have you done further testing to on this hot water heater? Does it work?
If you look at the edge of a piece of glass and it is a light green color, the glass contains some iron. The iron cuts down on the suns heat transmission. Clear glass lets the infared thru. Also when you seal the glass to the wood box , eventually you will get moisture trapped in the box.
While studying the coverings for collectors several years ago I found that Visqueen (trade name) plastic sheeting allowed more of the desireable infared rays into the collector. I used 6 mil thick sheeting. An added benefit was that the collector needed to be cleaned of dust periodically. The plastic sheeting was cheap and replaced when the dust was cleaned out..
Now that you have constructed a collector capable of producing steam, carry your experiments a little farther. Absorbtion refrigeration systems work on heat. An example is refrigerators in campers operating on propane.
At one time Absorbion refrigeration was popular in the south for airconditioning homes. Industrial plants use large absorbtion systems operating on steam to cool their office spaces. Carrier makes 100, 200, and 300 ton units. Several companies made units for homes. Bryant, Arkala, Servel, and two others were popular brands. Their airconditioning units worked fine. Their problem was in the servicing. The units were sold thru Natural Gas and Propane suppliers and their heating techs didn't know how to service the absorbtion systems. I attended a very large Solar Expo in Phoenix several years ago and the Japanese had absorbtion units on display that operated on solar collectors. Google Absorbtion Refrigeration to find out more.
You are to be commended for your achievements. The Instructable is well written and your pictures are clear and informative.
As for the covering: there are definitely better light transmitters out there. I was limited to what was on the shelf (built and tested in less than two days) I chose glass over plexi for light transmission and for it's durability to the sun. Plastics will often break down very quickly under UV exposure. Not sure how the Visqueen is UV rated.
Sealing the box: hindsight is 20/20 on that one. As you can see in the test photos the moisture trapped inside the box condensed on the glass covering. It was interesting to watch- the second I turned on the water hose and allowed cold water to flow through the coil the heat was immediately sucked out of the air in the box and the condensation was completely gone. It was a physics/thermo experiment all it's own.
Why not save all that effort and money and simply repurpoue a discarted fridge radiator?
Already designed for that purpouse, already black, adds extra blades that allow better heat exchange...
;-)