Outcome of my Pex Solar Water Collector project

[TheyCallMeDave]

Finally got it done and Im happy with the results .

The project consisted of building a Solar Box/Oven for 300' of 3/4" Pex-B Tubing to sit inside of and was built using 2x12's with a finished size of 36"x36" . 1/2" plywood was used for the backing with 1" Polyiso Board sitting on top of that with a thick piece of sheetmetal plate on top of that --- everything inside the Box was painted a flat black including the aborber plate, inner / outer box walls , and Krylon Fusion Paint for the Pex Coil . The top of the Box recieved a double pane Low E window in vinyl sash .

Filled the Pex Coil with cool 55 f. Well Water on a 90 F. mostly sunny day and waited 5 hours to take temp. readings :

Temp. inside Box : 161 f.
Exiting water Temp : 158 f.

(The Pex Coil holds about 6 gallons, but since i live alone ... it is more than enough hot water for my limited water useage for showers and occasional Dishwasher ; in fact, I have to cool it down alot with cold water at the Shower Head so Im using less than the 6 gallons of Collector Water. I have the Collector Water bypassing the Water Heater and going directly into the hot water line to the house . The Pex I used has a rating of 200 f. at 100 psi and the CPVC leading from the Collector Box to the house is rated at 180 f. at 100 psi. Total material cost : $350. ) .

[iamgeo]

Pics please.

[TheyCallMeDave]

Originally Posted by iamgeo

Pics please.

Short video forthcoming .

[DoctorDoctor]

160 degree water into the hot water line is dangerous! A mixing valve is mandatory. Here is one from Amazon: Amazon.com: Honeywell R-AM-101C-US-1 Thermostatic Mixing Valve: Home Improvement

The higher the temperature, the shorter the time to react before you suffer a second or third degree burn. There is a good graph here. Note that 160 degree Fahrenheidt allows for just a half second before such burns occur.

I am not sure where you would put the valve. Every sink, shower, or bath is a hazard.

[TheyCallMeDave]

Originally Posted by DoctorDoctor

160 degree water into the hot water line is dangerous! A mixing valve is mandatory. Here is one from Amazon: Amazon.com: Honeywell R-AM-101C-US-1 Thermostatic Mixing Valve: Home Improvement

The higher the temperature, the shorter the time to react before you suffer a second or third degree burn. There is a good graph here. Note that 160 degree Fahrenheidt allows for just a half second before such burns occur.

I am not sure where you would put the valve. Every sink, shower, or bath is a hazard.

Thanks alot for your genuine concern. I appreciate that. What i do is just crack open the hot water faucet for the shower and let it run thru at a fast trickle...then i open the cold water faucet to cool it down to somewhere around 95 f. Ive never burned myself doing it this way and im careful when i do it each time. Its great for the auto dishwasher and the plates and glasses come out real clean.

[TheyCallMeDave]

DAOX, per your request ----------------

DIY Solar Collector using Pex Coil tubing - YouTube

The project consisted of building a Solar Box/Oven for 300' of 3/4" Pex-B Tubing to sit inside of and was built using 2x12's with a finished size of 36"x36" . 1/2" plywood was used for the backing with 1" Polyiso Board sitting on top of that with a thick piece of sheetmetal plate on top of that --- everything inside the Box was painted a flat black including the aborber plate, inner / outer box walls , and Krylon Fusion Paint for the Pex Coil . The top of the Box recieved a double pane argon-filled Low E window in vinyl sash which has good light transmittance with ability to retain heat in the Box. Collector Box is on a 30 degree angle from vertical. Piped in parallel to the water heater so the house hot water supply is either fed by 100% Collector water or from the standby electric Water Heater (accomplished via bypass valves) .


Results after 5 hours of solar heating starting with 55 f. Well water :



EARLY AUGUST ----

90 f. totally sunny day (30 degree angle):
Exiting water Temp : 150 f.


93 f. totally sunny day (laying horizontal on the ground)
Exiting water Temp : 170 f.


84 f. totally cloudy day with mostly rain (30 degree angle) :
Exiting water Temp : 100 f.

Im still getting the same results now in MID SEPT .




(The Pex Coil holds about 6 gallons, but since i live alone ... it is more than enough hot water for my limited water useage for 100 f. showers and occasional Dishwasher ... and I always have hot water left over after showering for 10-12 minutes ; in fact on a sunny day I have to cool it down alot with cold water at the Shower Head so Im using less than the 6 gallons of Collector Water. . The Pex-B Tubing I used has a rating of 200 f. at 100 psi and the CPVC leading from the Collector Box to the house is rated at 180 f. at 100 psi. Total material cost : under $400 . This project is ideal for someone who has minimal daily hot water requirements ; more Pex Coils can be added for greater storage capacity to accomodate 2 or more people . The aim of this system was to keep it inexpensive , uncomplicated, without the use of a seperate water storage tank / controls / pump and to provide adequate hot water for One person) .




NOTES: UV rays are almost completely restricted by the choice of glass used, plus the Pex Coil is painted 3 times over with high quality plastic Paint.(simular installations with no UV protection at all, have been in operation for 6 years with no problems) .Expansion/contraction of the Pex Coil is no problem because extra space was left around the inner walls of the Box. No draindown required because hard freezes are very rare where im at. Copper was too cost prohibitive and doesnt handle freeze ups as well as Pex does. When the water is very hot (150 f. +), there is a slight plastic odor coming from the water when the hot water faucet is cracked open..but after a minute the odor greatly subsides and goes to nothing after a couple of minutes ; there is no skin irritation after a shower and its easy to rinse the soap off the body.

[TheyCallMeDave]

12-9-11 : Thought id post an update now its gotton 'cold' here in northern FLorida . Daytime temps outside are getting up in the high 50 f's , and with full sunshine and the Collector at a 30 degree angle from vertical .... at 4 pm which is when the sun just starts to go behind my trees.... Im getting a box/water temp. of 120-125 f. routinely so im delighted with that since all i require for showering is 100 f. Im still getting a full 10 minute shower by having to blend in some cold water at the shower faucet thereby cutting the flow of the hot as much as i can. I find I can take a shower in the evening as late as 8 pm if i want to but have gotton in the routine of taking it around 5 pm just before dinner . Dishes are coming out very clean in the auto dishwasher too .

A merry and meaningful Christmas to all in the NG. David.

[Daox]

Thanks for the update Dave. Its great to hear its working out despite this being pretty close to the shortest day of the year!