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Thread: Concerns about high pressure in flat-panel solar heaters

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    Concerns about high pressure in flat-panel solar heaters

    I have been researching with earnest several of the flat-panel black poly solar heaters, the 2'x20' and 4'x20' variety, and I see some mention of too much water pressure being a problem. We're about to mate probably a 4'x20' system like the SunGrabber with our new Hayward 50gpm pump and I don't want to blow it out. I guess having a diverter valve that could relieve some of the pressure on the collector is a must. None of these panels' selling information seems to give any information about operating pressures, except the lower-end models that state they are for Intex pumps and nothing else. If no restrictions are listed do I assume they will work with 50gpm? Has anyone else discovered the hard way it's important to have this information ahead of time?
    18'x4' AG Intex Ultra Frame, 6,700 gal., assembled new 2013; Mods: Hayward EC50C90 Perflex filter & 1 h.p. PowerFlo Matrix pump, Fiber Clear cellulose D.E. substitute, Hayward H100ID1 100,000 BTU NG heater, a pair of 2'x20' Sungrabber solar heaters via the original Intex 635T pump, grey Hydro Tools through-the-wall skimmer, Confer steps/ladder system & Cover Free chemical pool cover. The Summer of Mods!

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    JasonLion's Avatar
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    Re: Concerns about high pressure in flat-panel solar heaters

    You want roughly 1 GPM for each 10 sqft of panel area. If you size your panels just so there is no need for a diverter valve, but most setups use a diverter valve and don't send all of the water to the panels for exactly this reason.
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    cramar's Avatar
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    Re: Concerns about high pressure in flat-panel solar heaters

    My fafco's did mention something about pressure, I don't have the manual in front of me but it was something like not exceeding and additional 5psi at the filter gauge, or something like that. Not sure how relevant that really is though.
    They also recommend a diverter valve anyways, so probably best to use one.
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    Re: Concerns about high pressure in flat-panel solar heaters

    Quote Originally Posted by JasonLion
    You want roughly 1 GPM for each 10 sqft of panel area. If you size your panels just so there is no need for a diverter valve, but most setups use a diverter valve and don't send all of the water to the panels for exactly this reason.
    So at that rate my pump would handle a 500 sq. ft. collector. That's almost twice the square footage of my pool! Needless to say, I'll need a diverter. I'm guessing that once the system is plumbed, I'll just have to play with the setup to get the right amount of water moving through the panels. Any accurate way of gauging when I've found that sweet spot? I'm also considering adding on my existing beehive heater between the panels and the pool return, just for good measure.
    18'x4' AG Intex Ultra Frame, 6,700 gal., assembled new 2013; Mods: Hayward EC50C90 Perflex filter & 1 h.p. PowerFlo Matrix pump, Fiber Clear cellulose D.E. substitute, Hayward H100ID1 100,000 BTU NG heater, a pair of 2'x20' Sungrabber solar heaters via the original Intex 635T pump, grey Hydro Tools through-the-wall skimmer, Confer steps/ladder system & Cover Free chemical pool cover. The Summer of Mods!

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    Mod Squad jblizzle's Avatar
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    Re: Concerns about high pressure in flat-panel solar heaters

    No. Because you are very unlikely actually getting 50GPM (unless you actually measured that). That is the max you would see with no head loss.

    Your pump will support a collector of any size, but the flow rate would be below the optimal flow rates as the system gets bigger.

    I would suggest putting in a diverter valve, then as long as the panel feels cool to the touch, you have enough water flow through them ... no real need to be more exact than that.
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    Re: Concerns about high pressure in flat-panel solar heaters

    The way I do it is to slowly close the diverter a bit at a time and wait 30 seconds or so between moves. At some point the panels will fill, the vac release will close and water comes rushing down the line returning to the pool. From that point observe the pool, if there are still some air in the flow close the valve a bit further and call it good.
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    Re: Concerns about high pressure in flat-panel solar heaters

    Great information to have. So, does anyone have a preference as far as brand name? SunGrabber? EcoSaver? SunQuest? What?
    18'x4' AG Intex Ultra Frame, 6,700 gal., assembled new 2013; Mods: Hayward EC50C90 Perflex filter & 1 h.p. PowerFlo Matrix pump, Fiber Clear cellulose D.E. substitute, Hayward H100ID1 100,000 BTU NG heater, a pair of 2'x20' Sungrabber solar heaters via the original Intex 635T pump, grey Hydro Tools through-the-wall skimmer, Confer steps/ladder system & Cover Free chemical pool cover. The Summer of Mods!

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    Re: Concerns about high pressure in flat-panel solar heaters

    I decided to go with two 2'x20' Sungrabbers from eBay, which cost me a bit more than $200 with shipping. They arrived this morning around 10:30 while we were finishing off the hedge trimming, and by 12:30, I'm happy to report, we were pumping noticeably warmer water back into the pool! I did go with their diverter kit, which is nothing more than a 1-1/2" ball valve, two threaded tees and four threaded hose nipples. But I got everything tightened up and used just a bit of a turn of the valve, and when I had all the air out of the panels and my pressure had risen from 11 psi to 15, I stopped. Couldn't be happier right now and can't wait to get the pool up to my wife's temperature range

    I may come up with another set of tees so that I can plumb in the old beehive solar collector in parallel. Does anyone have some sort of elbow that comes off the manifold ends of these panels? Something other than just sticking a section of pool hose over them and clamping it?
    18'x4' AG Intex Ultra Frame, 6,700 gal., assembled new 2013; Mods: Hayward EC50C90 Perflex filter & 1 h.p. PowerFlo Matrix pump, Fiber Clear cellulose D.E. substitute, Hayward H100ID1 100,000 BTU NG heater, a pair of 2'x20' Sungrabber solar heaters via the original Intex 635T pump, grey Hydro Tools through-the-wall skimmer, Confer steps/ladder system & Cover Free chemical pool cover. The Summer of Mods!

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    Re: Concerns about high pressure in flat-panel solar heaters

    Here is a good video showing pressure considerations from Hot Sun Solar. A lot of good info on their site.

    http://www.youtube.com/watch?feature=pl ... lbQ_39QFeI

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    Re: Concerns about high pressure in flat-panel solar heaters

    Speaking of hot sun, they have a good, but somewhat hidden write up on the issue of overpressure on panels http://h2otsun.com/vahe.html

    As to the choice of solar panels, there are a number of good panels out there, some better than others, some cheaper and some more expensive, so not only do you need to decide if added cost is buying you a better panel, be aware this increase in cost is often only buying an increase in warranty length, some companies sell the same panel under multiple private labels at various price points with different warranty coverage periods, perhaps one of the often overlooked details is your location and way you plan to mount your panels. Are they going to be permanently roof mounted, or seasonal, for permanently mounted it is best to run the water flow up and down the roof line so the panels can completely drain, for a seasonal panel you may prefer one that you can roll up as opposed to a more rigid panel that would require more winter storage space, ....

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    Re: Concerns about high pressure in flat-panel solar heaters

    Quote Originally Posted by Isaac-1
    Speaking of hot sun, they have a good, but somewhat hidden write up on the issue of overpressure on panels http://h2otsun.com/vahe.html

    As to the choice of solar panels, there are a number of good panels out there, some better than others, some cheaper and some more expensive, so not only do you need to decide if added cost is buying you a better panel, be aware this increase in cost is often only buying an increase in warranty length, some companies sell the same panel under multiple private labels at various price points with different warranty coverage periods, perhaps one of the often overlooked details is your location and way you plan to mount your panels. Are they going to be permanently roof mounted, or seasonal, for permanently mounted it is best to run the water flow up and down the roof line so the panels can completely drain, for a seasonal panel you may prefer one that you can roll up as opposed to a more rigid panel that would require more winter storage space, ....

    Ike
    I did notice that it seemed the only difference between some panels was the warranty. I have mine plumbed on the ground for now. I'm searching for a good way to mount them so that I can offer a bit more protection. I can't see a good reason to construct a frame of some sort out of 2"x4"s though. I was thinking 3/4" or 1" Styro sheets, but how to strap the panels to them?

    Anyway, I have been struggling the past two days because the weather has murkily gone from partly cloudy to raining, and I don't know what's the best bypass pressure for my system. My DE filter was running at 11 psi before the install, and after I fiddled with the diverter the first day (nice and sunny) I wound up with fairly warm water returning to the pool. Now I'm beginning to doubt myself and have had the pressure as high as 17 psi and as low as 14. I'm planning to add the old GAME beehive heater in parallel. We'll see where the pressure winds up with that on the system.
    18'x4' AG Intex Ultra Frame, 6,700 gal., assembled new 2013; Mods: Hayward EC50C90 Perflex filter & 1 h.p. PowerFlo Matrix pump, Fiber Clear cellulose D.E. substitute, Hayward H100ID1 100,000 BTU NG heater, a pair of 2'x20' Sungrabber solar heaters via the original Intex 635T pump, grey Hydro Tools through-the-wall skimmer, Confer steps/ladder system & Cover Free chemical pool cover. The Summer of Mods!

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