Dreaming of a long soak in a hot tub in your backyard under a starry sky - maybe with a few good friends and a bottle or two of good wine?
Buying a hot tub will set you back at least $3,000 and probably a lot more. Then come the heating bills. But you can build a solar hot tub for under $400, with no heating costs at all. Free!
Making a solar powered hot tub is simple. You will have a great centerpiece for your garden, and it will work in any climate. The water will actually get so hot that you will need to fit a pressure relief valve for safety!
Begin with a good set of diy plans. These should include clear step-by-step instructions, a materials list, schematics and diagrams to show you exactly how to build the solar hot tub.
Basic parts of a solar hot tub system are:
• Solar collector panel
• Stock tub
• Filter
• Pump (optional, depending on the site)
• Various CPVC plumbing parts
• Pressure relief and control valves
A sheet of corrugated tin laid in a shallow wooden box is the basis of the solar collector. Make the box bottom from a sheet of ½ inch plywood, edges from 6 x 2 lumber or whatever comes to hand, and line it with a one inch sheet of insulating foam.
CPVC pipes (3/4 inch will do) are laid and fastened along the corrugations and connected in series allowing cold water to enter the solar collector at the bottom and exit at the top. Use CPVC for the plumbing, rather than PVC, because of its better heat tolerance. Paint the inside of the solar collector box and the pipes flat black, and close the top with a sheet of polycarbonate glazing.
Use a stand-alone tub of between 150 and 500 gallons, depending on how many will be in it! If you can mount the solar collector at least one foot below the tub to allow thermo-syphoning, you should be able to avoid fitting a pump. If this is not possible you will need a pump rated at about 150 GPH fitted at the outlet from the tub.
Pipe runs should be as short as possible, and avoid sharp bends. Fitting an in-line filter near the tub water outlet will avoid the task of having to clean out the tub from time to time. Finally you should fit inlet and outlet flow control valves as well as a safety valve to relieve excess pressure in the system.
Once you have tested the solar hot tub for leaks insulate as much as possible - any exposed pipes, the external walls of the tub, and the tub cover (vital to lower nighttime heat loss).
Any structure you decide to build around the tub will be for aesthetic or practical reasons such as access, since the tub is designed to hold its contents without external support.
The solar collector must be sited correctly. In northern latitudes place it facing due south, or within 10 degrees of it, and sloping at between 15 and 30 degrees from the horizontal. Also you should slightly tilt the solar collector lengthwise to promote the upwards flow of water through the collector pipes.
What time can you expect to take for heating the solar hot tub water? Depending on where you live it could take as much as two days to reach a comfortable 110 degrees the first time. Once there, though, you will find your main problem will be cooling the water rather than heating it!
Making your own solar and wind power for less than $200
Buying a hot tub will set you back at least $3,000 and probably a lot more. Then come the heating bills. But you can build a solar hot tub for under $400, with no heating costs at all. Free!
Making a solar powered hot tub is simple. You will have a great centerpiece for your garden, and it will work in any climate. The water will actually get so hot that you will need to fit a pressure relief valve for safety!
Begin with a good set of diy plans. These should include clear step-by-step instructions, a materials list, schematics and diagrams to show you exactly how to build the solar hot tub.
Basic parts of a solar hot tub system are:
• Solar collector panel
• Stock tub
• Filter
• Pump (optional, depending on the site)
• Various CPVC plumbing parts
• Pressure relief and control valves
A sheet of corrugated tin laid in a shallow wooden box is the basis of the solar collector. Make the box bottom from a sheet of ½ inch plywood, edges from 6 x 2 lumber or whatever comes to hand, and line it with a one inch sheet of insulating foam.
CPVC pipes (3/4 inch will do) are laid and fastened along the corrugations and connected in series allowing cold water to enter the solar collector at the bottom and exit at the top. Use CPVC for the plumbing, rather than PVC, because of its better heat tolerance. Paint the inside of the solar collector box and the pipes flat black, and close the top with a sheet of polycarbonate glazing.
Use a stand-alone tub of between 150 and 500 gallons, depending on how many will be in it! If you can mount the solar collector at least one foot below the tub to allow thermo-syphoning, you should be able to avoid fitting a pump. If this is not possible you will need a pump rated at about 150 GPH fitted at the outlet from the tub.
Making your own solar and wind power for less than $200
Pipe runs should be as short as possible, and avoid sharp bends. Fitting an in-line filter near the tub water outlet will avoid the task of having to clean out the tub from time to time. Finally you should fit inlet and outlet flow control valves as well as a safety valve to relieve excess pressure in the system.
Once you have tested the solar hot tub for leaks insulate as much as possible - any exposed pipes, the external walls of the tub, and the tub cover (vital to lower nighttime heat loss).
Any structure you decide to build around the tub will be for aesthetic or practical reasons such as access, since the tub is designed to hold its contents without external support.
The solar collector must be sited correctly. In northern latitudes place it facing due south, or within 10 degrees of it, and sloping at between 15 and 30 degrees from the horizontal. Also you should slightly tilt the solar collector lengthwise to promote the upwards flow of water through the collector pipes.
What time can you expect to take for heating the solar hot tub water? Depending on where you live it could take as much as two days to reach a comfortable 110 degrees the first time. Once there, though, you will find your main problem will be cooling the water rather than heating it!
Making your own solar and wind power for less than $200
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