My first DIY Solar hot water Collector using a 300' Pex Coil
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  1. #1
    Join Date
    Apr 2011
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    North Florida
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    32

    My first DIY Solar hot water Collector using a 300' Pex Coil



    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 :




    90 f. totally sunny day (30 degree angle):
    Temp. inside Box : 140 f.
    Exiting water Temp : 136 f.


    93 f. totally sunny day (laying horizontal on the ground)
    Temp inside Box: 160 f.
    Existing water Temp : 158 f.


    84 f. totally cloudy day with mostly rain (30 degree angle) :
    Temp. inside Box : 105 f.
    Exiting water Temp : 100 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 100 f. showers and occasional Dishwasher ; 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 if needed . 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) .

  2. #2
    Join Date
    Apr 2011
    Location
    North Florida
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    32
    Granted...if your hot water useage is alot...then this installation isnt for you. But for a single person who uses a minimal amount of daily hot water...it works very well and eliminates the need for a conventional Water heater providing you dont get extended days of no sunshine (which is never the case here in Florida) .

  3. #3
    Join Date
    Jul 2011
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    354
    i love this video, and i like the fact there are people out there that are just trying new ideas, you never know, how it may turn out, new ideas, imo, are always welcome.

  4. #4
    Join Date
    Apr 2011
    Location
    North Florida
    Posts
    32
    Quote Originally Posted by thes View Post
    i love this video, and i like the fact there are people out there that are just trying new ideas, you never know, how it may turn out, new ideas, imo, are always welcome.
    Thanks for the kind words. Its just amazing hot easy it is to harvest the suns energy for personal useage ; of course theres more advantageous areas of the Country to do this in such as where i live in Florida, but, good results can be had even in northern climates. I havent been thru a winter with my newly installed Project yet but if i dont get the desired 100 f. I need for my daily shower water at 5 pm , then at least i can use my standby Water Heater as a supplement . This morning when i left the house at 11 a.m. (on a totally sunny day) the Box Temp/Collector Water Temp. was already up to 135 f. ... and that was with the Box on the steep angle that it is right now (30 degrees from vertical) . Im going to lay it flat on the ground once my 36" flexible stainless steel water hoses arrive which will allow me to make seasonal angle changes fast and effectively.

  5. #5
    Join Date
    Jul 2011
    Posts
    354

    Cool

    Quote Originally Posted by JustCallMeDave View Post
    Thanks for the kind words. Its just amazing hot easy it is to harvest the suns energy for personal useage ; of course theres more advantageous areas of the Country to do this in such as where i live in Florida, but, good results can be had even in northern climates. I havent been thru a winter with my newly installed Project yet but if i dont get the desired 100 f. I need for my daily shower water at 5 pm , then at least i can use my standby Water Heater as a supplement . This morning when i left the house at 11 a.m. (on a totally sunny day) the Box Temp/Collector Water Temp. was already up to 135 f. ... and that was with the Box on the steep angle that it is right now (30 degrees from vertical) . Im going to lay it flat on the ground once my 36" flexible stainless steel water hoses arrive which will allow me to make seasonal angle changes fast and effectively.
    hey, good luck, really very interesting!

  6. #6
    Join Date
    Feb 2001
    Location
    N.E. Iowa
    Posts
    314
    Nice idea, but what about the PEX being exposed to UV?

    Normal PEX should not be exposed to ultraviolet light for a period longer than 30 to 60 days. PEX with UV stabilizers and protection shouldn’t be exposed to the light for more than six months.

    I know it would cost a lot more, but I would probably use copper or aluminum tubing due either material being a better conductor. The higher cost could even be offset by using salvaged materials that have been sterilized.
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  7. #7
    Join Date
    Apr 2011
    Location
    North Florida
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    32
    Quote Originally Posted by Fabrk8r View Post
    Nice idea, but what about the PEX being exposed to UV?

    Normal PEX should not be exposed to ultraviolet light for a period longer than 30 to 60 days. PEX with UV stabilizers and protection shouldn’t be exposed to the light for more than six months.

    I know it would cost a lot more, but I would probably use copper or aluminum tubing due either material being a better conductor. The higher cost could even be offset by using salvaged materials that have been sterilized.
    UV light was a consideration before i built this system ; it was one of the reasons i choose the Low -E double pane glass with argon gas fill as it eliminates nearly all of the UV light entering ... plus i painted the Pex Coil several times with good quality plastic paint. In addition, I talked with a guy online who used unprotected black irrigation tubing rolls to heat his Pool and its been in operation for 6 years now with no visible signs of deterioration or leaks...so, I feel confident mine will last quite a long time. My aim was to build something very inexpensively , compact, and simple...which is why i chose 200 f. rated Pex over Copper or ALuminum as it would have been cost prohibitive for six 50' rolls of 3/4" Copper . Im not hurting for performance with this installation...and in fact I dont even use the entire 6 gallons of 140 F. plus Collector water for a 10 min. shower at 5 pm as i have the hot water faucet only just cracked open at that incoming temp. When you introduce the Collector water directly into the house hot water line instead of trying to heat a 40 gallon tank with it...you just dont need much Collector capacity . I checked on the Collector Box inside temp / Pex Coil temp. early this morning...and after just 2 hours of direct suns rays on it...it was already at 125 f. -------- that was a 40 f. rise in 2 hours so I cant ask for better performance than that.

  8. #8
    Join Date
    Jul 2011
    Posts
    354

    Smile

    Quote Originally Posted by JustCallMeDave View Post
    UV light was a consideration before i built this system ; it was one of the reasons i choose the Low -E double pane glass with argon gas fill as it eliminates nearly all of the UV light entering ... plus i painted the Pex Coil several times with good quality plastic paint. In addition, I talked with a guy online who used unprotected black irrigation tubing rolls to heat his Pool and its been in operation for 6 years now with no visible signs of deterioration or leaks...so, I feel confident mine will last quite a long time. My aim was to build something very inexpensively , compact, and simple...which is why i chose 200 f. rated Pex over Copper or ALuminum as it would have been cost prohibitive for six 50' rolls of 3/4" Copper . Im not hurting for performance with this installation...and in fact I dont even use the entire 6 gallons of 140 F. plus Collector water for a 10 min. shower at 5 pm as i have the hot water faucet only just cracked open at that incoming temp. When you introduce the Collector water directly into the house hot water line instead of trying to heat a 40 gallon tank with it...you just dont need much Collector capacity . I checked on the Collector Box inside temp / Pex Coil temp. early this morning...and after just 2 hours of direct suns rays on it...it was already at 125 f. -------- that was a 40 f. rise in 2 hours so I cant ask for better performance than that.
    hey, keep doing your thing, get the bugs out and let us know how you made out, back in the 80"s i got a flat tire, so i put on the donut tire, i ended up driving down to florida and back to NY,with the donut tire on, over 4,000 miles, and then some one told me that you should only drive 30 miles on a donut tire! to bad no one told the donut tire to only last 30 miles. ps i'm not recommending driving 4000 miles on a donut tire, but my MPG'S where never so good with that tire on!

  9. #9
    Join Date
    Feb 2001
    Location
    N.E. Iowa
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    Quote Originally Posted by JustCallMeDave View Post
    I talked with a guy online who used unprotected black irrigation tubing rolls to heat his Pool and its been in operation for 6 years now with no visible signs of deterioration or leaks...so, I feel confident mine will last quite a long time. My aim was to build something very inexpensively , compact, and simple...which is why i chose 200 f. rated Pex over Copper or ALuminum as it would have been cost prohibitive for six 50' rolls of 3/4" Copper.
    I wasn't trying to tell you you had done anything wrong. I was just making an observation.

    In fact, I applaud your efforts. I'd be interested to see how long the PEX holds up. It has been in use for about 30 years in Europe and I haven't heard of any issues other than some cracking of brass fittings. Most PEX manufacturers only warranty the product for 25 years.

    I installed a basement shower in my home 3 years ago using 15' of 1/2" PEX supply lines and I can still smell the chemical off-gassing when I take a shower. I can imagine what 300' of 3/4" must smell like at 140°. Have you noticed any peculiar smells with your installation?
    ______________________________________________

    Sign petition to limit Congressional and Senatorial terms. http://www.termlimits.org/

    "We may have all come on different ships, but we're in the same boat now."--Martin Luther King Jr.

  10. #10
    Join Date
    Apr 2011
    Location
    North Florida
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    Quote Originally Posted by Fabrk8r View Post
    I wasn't trying to tell you you had done anything wrong. I was just making an observation.

    In fact, I applaud your efforts. I'd be interested to see how long the PEX holds up. It has been in use for about 30 years in Europe and I haven't heard of any issues other than some cracking of brass fittings. Most PEX manufacturers only warranty the product for 25 years.

    I installed a basement shower in my home 3 years ago using 15' of 1/2" PEX supply lines and I can still smell the chemical off-gassing when I take a shower. I can imagine what 300' of 3/4" must smell like at 140°. Have you noticed any peculiar smells with your installation?
    I didnt take your previous post offensively and im sorry if i sounded that way.
    I do get a very slight plastic odor when the collector water first starts coming thru the shower...but it seems to dissipate during the shower. Another concern i had was the expansion of the Pex Coil in my Collector Box as i read that it expands and contracts quite a bit with temp. changes...so i left a good 3" of empty space on the inner walls of the Box for the Pex to do its thing. I guess the real test will come during the Florida 'winters' when it only gets up to 55 f outside , yet with full sun light each day --- my minimal requirement for shower water is 95 f. so im hoping I will have at least that after 8 hours sunshine during the winter. ALso, I dont have to worry about draindown of the system as i seldom get a hard freeze plus PEX handles freezing and thawing better than copper I read . At this point, I dont know if id do anything differently on the installation...except perhaps put on 36" long stainless steel flexible water connectors so i can tilt the Collector Box from 30 degrees to laying horizontally on the ground to accomodate seasonal sun angles (instead of hard piping the Collector Box) ... but i have those on order right now.

  11. #11
    Join Date
    Oct 2011
    Location
    St. Louis MO
    Posts
    5

    Nice

    I love the video and congrats on building it and doing it. I owned a solar company for a while here in St. Louis ( I since sold the company). Another Idea for your box that may help is the same concept the solar ovens use. I am talking about the four sides that open up at an angle to the box portion of the oven. Here is the link http://www.sunoven.com/I own one and the temps are easily 400+ degrees (depending on time of year)

    Here is one of my first inventions

  12. #12
    Join Date
    Apr 2011
    Location
    North Florida
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    32
    Quote Originally Posted by Thermasi Overload View Post
    I love the video and congrats on building it and doing it. I owned a solar company for a while here in St. Louis ( I since sold the company). Another Idea for your box that may help is the same concept the solar ovens use. I am talking about the four sides that open up at an angle to the box portion of the oven. Here is the link http://www.sunoven.com/I own one and the temps are easily 400+ degrees (depending on time of year)

    Here is one of my first inventions
    Saw your first invention...very slick. I can see this catching on nationwide.

    I really like that Solar Oven and how its so easy to setup right in the box that it comes in. Very cleverly done and effective if it reaches 400 f.

    For my personal hot water needs, I dont need anything more efficient than what i built ; now we are into October (northern FLorida) , im still getting the same results as i did in August and the ambient temperature during the day is at least 12 f. less . The hottest water temperature in my Solar Collector occurs at 3-4 pm and is almost always 160 f. on a total sunny day --- Ive sometimes delayed taking a shower until 10 pm at night and the water is still 130 f. + . Im hoping for good results during Florida winters when the sun is lower and the ambient temp. is only 55 f. Ive got the collector propped up at a 30 degree angle from vertical now until next May.

  13. #13
    Join Date
    Jan 2011
    Location
    greenville , sc
    Posts
    718
    get that designe filled with glycol and add an auxillary coil and blower and you have an effective heat exchanger...


    cool ideas man very cool...
    catch a man a fish , feed him for a day.
    teach a man to fish , ruin a good business opportunity.

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