Solar hot tub???

[colebrookman]

Anyone using solar for outdoor hot tub heating? I've got a 500gal tub with a broken heating element that I would like to convert to solar. By not using the tub we have cut our electric bill almost in half during cold weather. But we really miss soaking the old bones and watching the stars; no light pollution in the hilltowns. A web search turned up mostly pool heating in spring and summer. Any ideas?

 

[Highbeam]

I will take a dip tonight in our tub that is 8x8 and about 500 gallons. These things take a lot of energy. Electric is 100% efficient and I had to run a 60 amp service for this thing. 60 amps of 220! So you need to collect one heck of a lot of solar energy. It needs to be dense too since you are trying to heat the tub past 100 degrees. Easier to heat a pool to 80.

 

[Redox]

Years ago, I used to service a health club that had a solar collector piped in to their whirlpool. I'm pretty convinced that it radiated more energy than it collected.

The problem is that you have to maintain a very narrow temperature range and this is going to be near impossible, unless you never take the cover off. You might be able to get the water up to 100F, but as soon as you take the cover off, there goes all your heat. Hot tubs don't really use a lot of energy if they are well insulated, but they need a huge heater to keep up with the evaporation.

Just for fun, try running the pump on high speed with the air shut off for a while (cover on). The heat generated from the pump and moving water might actually heat up the water to a usable level if your insulation is good enough. I used to do this in mine when the element burned out and was actually able to get the temp up well over 100F! It isn't any more efficient than an electric heater, though.

For more fun, you can try "The Snorkel". No, it's not a position... :coolgrin:

http://snorkel.com/hot-tub-info/snorkel-and-scuba-stoves.php

I think I've seen someone on here that uses one.

Chris

 

[colebrookman]

Thanks for the replies guys. We loved the hot tub but we feel guilty using all that electricity and keeping 500 gals hot outside. We only need 100* because we love to sit and enjoy the time out from life. It's hard to forget about the old yankee thrift and not be to extravagant. I've considered wood heating but that becomes a chore and you would need to dump the water each time in freezing weather. We are considering going to a soaking tub with 150 gals. or so but the are not very spacious. Maybe going to solar electric would work and also ease our conscience. It's a work in progress.
Ed

 

[Highbeam]

"we love to sit and enjoy the time out from life"

Some people go to bars, keep horses, go out to dinner, to watch movies at theatres, or whatever and those things cost lots of money. Your joy in life might be that tub and that's just fine. If times get tough you can shut it off and pay nothing which is more than can be said for a horse.

The hot tub does not waste good drinking water, does not overload your septic system, and is always hot and ready. Ours is outside so we can watch the fog roll in or the stars. I taught my daughters which stars made up Orion this weekend. We can fit the whole family in there and nobody is watching the TV. We just talk with the captive audience. Try fitting 5-7 people in the bathtub.

Replace the element.

 

[colebrookman]

"we love to sit and enjoy the time out from life"

Some people go to bars, keep horses, go out to dinner, to watch movies at theatres, or whatever and those things cost lots of money. Your joy in life might be that tub and that's just fine. If times get tough you can shut it off and pay nothing which is more than can be said for a horse.

The hot tub does not waste good drinking water, does not overload your septic system, and is always hot and ready. Ours is outside so we can watch the fog roll in or the stars. I taught my daughters which stars made up Orion this weekend. We can fit the whole family in there and nobody is watching the TV. We just talk with the captive audience. Try fitting 5-7 people in the bathtub.

Replace the element.

You mean we have to give up all the above. Just kidding but you have quoted my wife almost exactly. We do get a lot of enjoyment from the hot tub and the grandkids love to soak and watch the stars when they come up. I guess I'll try to retrofit some kind of heater. It's an old model with no parts but I bet the heating element is assembled from off the shelf parts. Now if it wasn't 6* outside!! Many thanks for the feedback.
Ed