I have a thick cover on the tub. I set the tub for 102 degrees, and on warm
days the solar panel will get it up to 105-106, which is a tad warm. By
morning it might be down to 104. I estimate about a degree a day of loss
during the summer without anything connected to the tub. The solar panel
keeps it up around 102-104 during the spring/summer/fall months with no
electricity use. This is a smaller tub (300 gallons). If you have a large
tub, you might need two panels (400′ of tubing).
Thank you very much for sharing. I also think it could be more efficient to
allow the water to heat more time before pumping it in the tub. I have
hooked my solar boiler to a storage tank and pump the water each hour, the
max. temp. difference (solar boiler) is about 40 degrees Celcius. The
capacity of the solar boiler is 6 litres approx., the storage tank about
60. Depending on the sun, at 15.00 O’Clock the temperature of the water in
the storage tank reaches about 45-50 degrees Celcius.
Hmm I see, I thought the thermostat ran the pump and would hold water in
the hose until it got hot then shut off when it got to cooler water thus
cycling the pump. different flow rates resulted in only different cycle
times. With your design working so well though, I am going to replicate
your design as closely as possible. Thanks for the info.
You can still find the pump on Ebay. Search for “12V water pump P-38I”:
Rated voltage: 12V DC Rated current: 0.57A Capacity: 6.5L/Min (103GPH) Pump
head: 2M Noise: <=55dBA/10cm Working temperature: -35C ~ +105C Service
life: 26000 hours up Motor: DC brushless motor Pump: Centrifugal pump
Update: It’s been in the 80s for the past few days and the tub has been
running between 104-106, with no supplemental electric heat. I have the
thermostat set at 101, so it never turns on. Even with temps in the 70’s,
the tub stays around 102-103.
I like your heater but I live in Colorado so using water will not work with
sub 0 temps. What do you think about running the output lines to another
coil of .5 ABS coiled up as it comes from the hardware store set inside the
hot tub. The system would them be closed and I could Antifreez.
it would work OK with an inflatable pool. You’d be better off with a bigger
pool solar panel for a pool though. A pool needs a lot of water raised a
few degrees, where as a hot tub needs a little water raised to a higher
temp. This design circulates a little water slowly, thus raising the outlet
temp to >104. A pool solar panel might raise water a degree or two at the
outlet, which does fine for bring a large pool from 68 to 80deg, but no
good for a hot tub.
@bjames1200 My pump only pumps about 45gph. 500gph is probably overkill and
will cause the water to flow too quickly through the tubing. If the water
flows too quickly, it won’t heat up enough. I’ve had this hooked up for the
past couple months, and the electric heater on the hot tub has only kicked
on a handful of times. In fact, I think I need add a high temp cut-off on
the panel intake because the tub as actually getting too hot (104-106), and
it isn’t even summer yet!
I think I said in the video that I used 5/8″ tubing, but it really is 1/2
in tubing. 5/8″ would work fine, maybe even better for a large tub. I used
a roll (from home depot). I think I used about 200′- it was only about $10
for the tubing.
It’s been freezing at night lately, but barely. I’m not sure it would do
well in a hard freeze, especially the pump. It does not drain down at
night, but if you used a larger pump you could probably work out a drain
down system. The small pump needs to stay primed all the time, and the
siphon effect helps move the water.
you are correct, i know alot of people who think it is fake. Listen, i’ve
been getting paid about $200 a week just selling energy. I took the idea
and plan of here. you can also try it: FREEENERGYGENERATION.PIXUB.COM