Solar Hot Water Heater Batch Pre-heater





Introduction: Solar Hot Water Heater Batch Pre-heater

This is a Solar hot water Batch Type pre-heater that pre-heats the water for my hot water tank inside the house. Cost $45.00 to build. I made it out of garage sale and Goodwill items and scrap wood I had laying around. It has been heating water up to 140 degrees and circulates thru the tank by natural flow no pump needed as it is lower than the main tank.

Step 1:

This is what it looked like when I finished. I added extra insulation and foamed all the cracks.

Step 2: Parts and Pieces

This is a fresh water tank from an old camper trailer that was given to me. This project can be scaled up or down to suit your needs.

Step 3:

A piece of old peg board, A sheet of masonite would have worked better but this is what I had.

Step 4:

Cut frames and sides from scrap plywood. This is not the true curve but it is what I had for material.

Step 5:

3 pieces of .50 cent glass. Foil backed styrofoam board ends scrap from a garage remodel.

Step 6:

Tank painted .96 cent Wall Mart black. 99 cent space blanket glued to the peg board.

Step 7:

Box with glass added. Not attached yet, time to start plumbing.

Step 8:

I ran the hoses inside some old PVC, wrapped in strips of old foam bed pads for insulation. I put 2 valves in case I have to drain the outside system if it gets too cold this winter.

Step 9:

Built a box around the fittings, with an access hole to reach shut-offs. I'm making a small garden box under pipes. The Bird bath is two gum ball machine stands, one upside down and inserted in the up right one. I have been doing a little art lately, You can check it out at my link.

Step 10:

Added another 1/2 inch of foil backed insulation and painted to match skirting. Sealed all the cracks with silacone sealant.

Step 11:

Cover for back of tank. I plumbed in a temp. meter from a car that tells me the temp. of the water in the top of the tank. I can see it and an outside temp. from in the house.

Step 12:

110 degrees at 9:30 AM. Not bad for a junk yard heater!

Step 13:

This is a new system I have been working on, It heats a 40 gallon tank under the bathroom floor that radiates heat thru the floor all night. So far it has been working great, it has warmed the tank to 120 degrees on a nice day. I will post a new instructable on this one later, when I have a few stats on it. I will be draining the system and filling with R.V. antifreeze soon.

Step 14:

Here is a rough drawing of how I plumbed it but most applications are different depending on the tank etc. always use pressure hose and have a pressure relief valve. Sorry about the drawing I'll try it again later.

Step 15: Winter Testing

Snowy morning in Washington. Made it to 110 before noon. Outside temperature got up to 55. It reached 130 in the hottest part of the day. I think the reflection off the snow helped raise the temp. today. The last picture is all my experiments. In front is a small solar panel I made out of 20 broken garden lights. I will start an instructable on it next week to enter that contest for the laser cutter. Next is a solar water panel that heats a 50 gal tank under the bathroom floor and radiates heat out all night. Behind that is this instructable, behind that is my solar oven.



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    25 Discussions

    Very excited to try this. Do you have any safety measures to suggest if the temp goes dangerously hot?

    What a great idea! I am considering trying a solar heater for my pool(30 ft,round, 52" deep, approx 10,000 gals) I am only looking to pick up about 10 degrees to 75-85 F. Do you think this is feasible? would a batch style be the most effective? Would an old water heater tank be large enough? I have unobstructed sun all day. All comments or suggestions would be greatly appreciated.

    6 replies

    This combined with perhaps fresnel lenses, or parabolic mirrored dishes, etc, could theoretically give you near boiling hot water on demand as long as you tracked the sun with it. However the addition of a tank would allow for hot water at night, and would help make sun tracking far less critical. See Kingofawesome's Fresnel lens projects.

    Hi I think your idea sounds OK. I would try for a least 30 gallons and a larger box, about the size of an old sliding glass door. I see them in garage sales all the time. Getting the correct curve would make it heat better also.I just used what size I had available. Insulate as good as possible and double glass if you can find it. I am very happy with the output of this one, on nice days I don't turn on the electricty to my main tank. Good Luck with your project.

    Thanks for the input. I'm finalizing plans now and will hopefully install and test late April/early May and will post results.

    I have a 28,000 gallon pool in NJ with all day sun (when it's shining). I was about to buy a $150 solar collector panel (black poly with many individual channles..made for pools)to test functionality and was poking around for DIY ideas instead. Did you have any luck building this? I'm curious how the constant flow you'd have with a running filter impacts the ability to heat the is the flow too fast for the collector to warm it up?

    Hey I've thought of this too, was wondering if it would be better to make something with more surface area, using black hose, since the water is flowing constantly. I've seen models that go on a roof with small black hoses. My idea was to use a hose run back and forth inside a box like this,

    THere is another way to want to warm your pool. Cover the pool so you decrease the evaporation. The change of state of water consumes many more calories then radiant heat loss. I have even heard of nets holding foam blocks that just decrease the surface area which loses heat by evaporation.

    you want a layer of foil on every household roof. With the foil reflecting the light into the center of the street, warming your thing in a cylindular form.

    Very nice design for the pre-heater. I'd like to build one to pre-heat the water that goes into my automatic dishwasher, to save the electricity that the washer uses for pre-heating. It would need to heat 4-5 gallons to 140-150 degrees F. I think the most difficult part would be the plumbing.

    excelente idéia. temos muito sol aqui no brasil e irá funcionar muito bem!!!

    Hi Yes you can add it, I hope it helps someone get started. It has been working great now that we got our sunshine back.

    i love this site -- i love you guys -- i.........I'm getting carried away here -- good job !

    The nice thing is it costs little to build, less to maintain, and nothing to operate. Even if you build a system that just suppliments your present system, every bit of energy you harvest is money saved. It amounts to turning sunlight into money! Thanks for sharing your expertise with us.

    Hi Not much progress on this project. It was working great for a few months but I had to drain it in this freezing weather. I have some small leaks so I won't put the RV antifreeze in till I get new hoses. I added a remote wireless temp. unit so I can monitor the water temperature from the living room. I will take more pics and start a new instructable when the weather clears up.

    Very cool... er, hot! I would like to have seen how you hooked it into the plumbing with a diagram and some pics.

    I will surely be waiting for that instructable! Theres nothing like a warm floor on a morning shower! Thank you!