Copper rolls come in 60' rolls which makes it easy and compact to build a Solar Collector around. I reckon one roll would provide enough hot water for a 40 gallon water heater in FLorida...but another roll could always be implemented easy enough. Price on a roll of 3/4" copper runs about $140 with maybe another $50 in misc. collector box materials, making it awefully inexpensive . A suitable heavy duty water pump runs about $140 ,
What do u think ? Have you got a solar collector ? Please share. Thanks.
snipped-for-privacy@gmail.com wrote the following:
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I have about 100' of black plastic tubing which I use to help warm the inground pool water in the late spring-early summer. The pool water is about 55-57º F when I open it. Within a week it is in the 70's. The tubing is coiled with 4 wooden spacers of my own making to keep it coiled without overlapping. It is about 8' feet in diameter. One end has an adapter to screw it into one of the dischargers, the other un modified end just spills into the pool.
About 45 years ago (mid 60's) my dad & I built a "solar pool heater" out of 20' sticks of 1/2" (nomimal; 5/8" OD) copper tubing. We used U-fittings ....lots of soldering. And we placed the tubing assembly, two or three layers to minimizing "self shade", in "box" with glass cover.
It worked ok but the box foggedd up with condensation & we abandoned the concept......
A number of year later (after a re-roof) I convinced him to forget the box and just place old tubing in a single layer on the shake roof.
In the early 70's when solar collection became quite the rage....an engineering prof asked me to collect data on the system input water temp output water temp sort description of "weather"
My dad was working the swing shift at that time and was more than happy to take data for us a couple times per day.
The house (& pool) were ideally suited to solar collection....back yard, pool & main roof (single story ranch) all ran east & west. The roof angle was just about optimum for summer time heating. House location was Orange County, CA.
ing, use latitude plus 10-15. For year around heating, install the collecto= rs at latitude. Variations from these ideals can be compensated for by addi= ng additional collector area.
ating, use latitude plus 10-15. For year around heating, install the collec= tors at latitude. Variations from these ideals can be compensated for by ad= ding additional collector area. from
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Thanks everyone for responding. Bob....what do u figure the required GPM is thru a copper roll collector ? Is it better to really have the water moving thru it, or, slow it down for greater heat pickup ? Ill be using the copper roll collector in conjunction with a regular 40 gallon electric water heater for Mobile Homes which have the accessory top hot/cold ports plugged and ready for piping from a solar collector. Im pretty excited about building the collector and installing everything....as I think it will satisfy 100 percent of my domestic hot water needs since i live alone. I dont know if to use
Wow...thats pretty impressive considering your pool was probably a couple thousand gallons volume . I want to go with copper as i want it to last a very long time without leaks.
heating, use latitude plus 10-15. For year around heating, install the coll= ectors at latitude. Variations from these ideals can be compensated for by = adding additional collector area. > from
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IBB-
This is really straining my memory ...... :)
but the only "gotta remember" numbers
are BTU/hr/ ft of copper tube (10 BTU/hr/ft of tube) and the total length of the collector (like 480 ft, more or less)
The flow thru our collector was only ~1/2 gpm......we kinda "got what we got", we had branched off the pool return line and routed a buried
3/4" PVC pipe through the flower bed around the pool (about 40' or so)
We could have reduced the flow by throttling it back or increased the flow by re-piping the 480ft total to be in a series of parallel circuits.
The temperature rise across the unit was about 5 to 20F degrees depending on sun.
Just off the top of my head ..... I would recommend balancing the flow rate with collector "flow length" / temperature rise. For heating a pool, you just keep recirculating the water.
Domestic water heaters are a different story..... I don't really have any experience with domestic water heaters
y heating, use latitude plus 10-15. For year around heating, install the co= llectors at latitude. Variations from these ideals can be compensated for b= y adding additional collector area. > > from
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Well thank you in any case for sharing what you do know. Its an intriguing concept especially when you live in FLorida where the sun shines alot and the suns rays are intense...even when its 55 f. outside.
Many people have their solar collectors removed when they get their roofs reshingled, so you should be able to get them cheaply or for free from roofing companies. That's how I got the four panels at no cost, and they were good ones made of extruded aluminum, tempered glass, and copper tubing on aluminum extrusions. I think people toss their solar heaters when they need a repair and are told a new pump or tank will cost $500-$1,000, installed.
Commercial 3' x 6' collectors will have 5-6 rows of 1/2" copper tubing. Ours have the tubing pressed into aluminum extrusions made for solar, but others may have the tubing soldered to 6"-8" wide strips of copper flashing (can be very thin) or a piece of galvanized steel (not as thermally efficient but good enough). It's easier if the tubing goes on the back because it makes painting the surfaces easier. Black barbeque or exhaust pipe paint works fine but has to be fully cured with heat lamps or else the glass will fog up inside. Also you don't want the tubing or the collector plate metal to touch the metal box at all or heat will be short-circuited to the outside. Isolate the tubing with pieces of fiberglass cloth or insulation, and use rubber grommets where the tubing has to pass through holes in the box. A lot of collectors are insulated with foil-backed rigid foam isocyanurate or urethane (styrofoam melts too easily) made into a box (glue with silicone rubber sealer), foil facing inward.
In a mild climate like Florida, don't rule out simple recirculation for freeze protection because it can save a lot of money by not requiring a heat exchanger (open loop water, no closed loop antifreeze) and allowing a much smaller, weaker pump to be used (1/100 HP, only 4-5' of head -- must open an indoor hot water faucet to get the system primed). But have at least two freeze sensors, one for the outlet, another for the inlet), each calibrated for 37=B0F, not
32=B0F. The pump needs a spring-loaded check valve on its outlet or thermosiphoning will cool off the water in the tank at night. Also this type of system can use a regular water heater. It can be used as- is and without power connections in a 2-tank system (probably best for gas), but for a 1-tank system the tank can be modified by disconnecting the bottom heater and shortening the dip tube so it extends only about 6" below the top heating element. The drain valve now serves as both the cold inlet from the water supply and also the outlet to the pump.
heating, use latitude plus 10-15. For year around heating, install the collectors at latitude. Variations from these ideals can be compensated for by adding additional collector area. >
You get more energy transfer from the highest temperature differential. All other things equal, more flow, lower temperature rise, results in more captured energy. Also reduces loss in the piping to/from the collector.
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