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stmbtwle

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Reply with quote  #51 
Fittings are easy. In the plumbing section of Home depot and probably other stores you can get REINFORCED clear vinyl tubing. It takes the heat well and comes in sizes that match CPVC pipe, so you can glue ordinary CPVC fittings to it with CPVC cement. You can also glue smaller diameter hose into larger hose for an "adapter". Of course you can always clamp it too. It does get hard over time but I've never had it fail. Just be sure you get VINYL and NOT polyethylene, which you cannot glue.

Vinyl garden hose also seems to work well. It slides over 1/2" CPVC pipe and can be glued or clamped.

For long runs PEX is probably best, but it cannot be glued and requires special tools or expensive fittings.

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Willie, Tampa Bay

Rick H Parker

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Reply with quote  #52 
"For long runs PEX is probably best, but it cannot be glued and requires special tools or expensive fittings."

PEX piping is highly susceptible to damage by sunlight, not well suited for outdoors installation unless covered.  Other then that, PEX is good stuff. Maximum operating temperature is 180 - 200 degrees Fahrenheit, depending on manufacture, read the fine print.

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Rick H Parker
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stmbtwle

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Reply with quote  #53 
True but pretty much the same applies to CPVC. Anyway, it's likely to be insulated which will protect it from UV. Also bear in mind that PEX and CPVC are rated for 100 PSI at that temperature. At the low pressure most DIY installations run at, it's not really a problem. My copper collector frequently stagnates and blows off steam (212F). No big deal for either CPVC or PEX.

Then there's auto heater hose.

1-1/2" thinwall PVC pipe slides nicely over 1/2" pipe insulation, protecting it and the enclosed PEX or CPVC from UV and rodents. Looks good too, and can be painted. For 3/4" pipe you'd probably need 2".

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Rick H Parker

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Reply with quote  #54 
Tori is new at this, I figured it would be a good idea to bring up the subject. Could save the guy some time and money in the long run.

Is your copper collector pressurized? As the pressure goes up so does the boiling point. Selecting a venting pressure just below the weakest point in the system would raise your boiling point, if you have not done so already.

This is how they keep automotive radiators from boiling over.

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Rick H Parker
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stmbtwle

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Reply with quote  #55 
It's not pressurized. When it reaches boiling it blows steam and hot water out the return line to the storage tank. When it was connected to the hot tub I had to install a vent line so it would't overheat the tub. I also had to install a clapper valve to keep the hot water from blowing back into the pump. The 4x8 collector was WAY too big for my little tub, I eventually replaced it with a 2x4 ARETHA.

The copper collector is currently installed on my space heater. The pump shuts off at 160F (storage temp) to keep from overheating the poly storage drum. This of course causes the collector to stagnate and I get a little steam blowback but not enough to be a problem. The collector is higher than the storage, so once it boils dry the blowback stops. In summer when the system isn't needed I swing the collector to vertical to minimize heat harvest.

My solar DHW IS pressurized, but it's fitted with a P/T relief valve like any water heater. THAT system is 100% copper, heat isn't a problem for it. It's set to run at 170F and I'm sure the collector gets hotter than that. I installed a tempering valve (now required by code) to prevent that hot water from getting into the distribution lines and presenting a scalding risk.

Tori your hot tub only runs at about 104F max, and my guess you'll need a high limit switch for safety. Problem with that is that when it shuts off the pump the collector will keep collecting heat and will get hotter and hotter. Being plastic it may melt. Summer is coming on so you may want to leave the Suntuf glazing off at first, or be prepared to cover part/all of the collector.  At least leave the ends open.

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Solar is like the wind. It may be free, but putting it to work isn't!
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Tori

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Reply with quote  #56 
Collector is Poly tubing.  It's not able to build pressure since it's open at each end.
Rick H Parker

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Reply with quote  #57 
"Collector is Poly tubing.  It's not able to build pressure since it's open at each end."

When you pump water through, the walls of the poly tubing will build pressure. Pumped water is under pressure, it wants to expand in all directions.  The faster you pump the higher the pressure.

That is one of the reasons Willie is trying to advise you, not to go hog wild on the GPM.

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Rick H Parker
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stmbtwle

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Reply with quote  #58 
Pressure shouldn't be an issue, at a few gallons/min through 3/4 or 1" pipe and say 110F temp. The PUMP can only develop about 5 psi. I think the only problem is possible overheat when stagnated.

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Tori

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Reply with quote  #59 
Overheating the tub is not a concern. Our sun is not that hot, even in summer.   System has been sitting idle for months without any issues.  
stmbtwle

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Reply with quote  #60 
Then you should be good to go! (I keep keep thinking Florida, it gets HOT)
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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
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