.........and it still works!

[Gotcha6]

A couple years ago I dumpster dove a building directory from a project I was doing. I always knew what I'd do with it, and finally this spring I did it. It is an aluminum frame with about 6" of depth and an acrylic cover (hinged). So. I got me a bundle of 1" thin wall PVC pipe and a couple bags of tees, some elbows, and adapters, and some black paint. Cut some 2" Styrofoam I had for backing, & 2 hours later, voila! I had a solar water heater for my pool. LOML likes the water warmer and this gets her in sooner. It was hooked to a sump pump with water hoses and put on a timer. It will raise the water about 4+ degrees on a pass on a sunny day.
Well, on Thursday, Murphy took over. This is what it looks like after the GFCI tripped out that morning and the water got a little warm:



Ironically it still works, & with the pipe flattened out it probably gives more heat transfer than before. I think I'll leave it this way for awhile.

 

[Glennbear]

Very inventive Dennis, I am glad it still works. :wsmile:

 

[Mark Stewart]

a friend of mine did something similar except he uses copper tubing ab=nd says this is the ticket.
Nice woirk there dennnis. Recycle where ever you can these days.
I did read an article some time back on making a small solar room heater with this same principal. It used copper pennies with a sealed bob cut slits in both ends and set it in a window said in a 10 x10 room would add 2 deg not bad for free I guess

Thanks Mark

 

[Gotcha6]

I was reluctant to use copper because of the corrosive nature of chlorinated pool water. I already had some copper radiator tubes from the hydronic baseboard heating system removed from my former home, but felt they wouldn't last. Most components used around pools today are either plastic or stainless steel.

 

[Guy in Paradise]

So, how could this have been prevented?

Would a temperature or pressure relief valve of some sort have prevented the overtemping? Looks like a great idea.

 

[jhreed]

What would it have cost to have the exposed surface area of the tubing expanded like this? Me thinks you got it done free!!
James

p.s. My BIL had a heater on his pool. It was about the size of a 10 ton heat pump and the natural gas line feeding it looked to be 2". He never used the heater for fear of the cost.

 

[Gotcha6]

Re: So, how could this have been prevented?

Would a temperature or pressure relief valve of some sort have prevented the overtemping? Looks like a great idea.

Since it is only using pool water for a thermal medium, I fear the results would have been the same if the relief valve or pressure valve had been a component. With a free flow from the pump and an open system there is no pressure to build. Sump pumps usually only produce about 12-15 psi with a reduced output as the head increases. The idea of a vacuum breaker occurred to me, but since it appears the system never lost its charge of water, the results would have been worse. Placing thin wall - or even Schedule 40 PVC piping behind an acrylic surface and exposing it to 90+ degree sunlight without adequate circulation will get similar results. I had even thought of turning the pump back on and plugging the discharge hose to see if it would open up the pipes again.
Any metallic piping would have survived because of the inherent heat resistance. My next thoughts on design would be to use PEX, but it is considerably more expensive on the fittings side. All in all, I'm out ~$50 worth of tubing and a couple hours labor. A fair tradeoff for the experience, but I still don't see how to avoid the consequences of a power failure unless the system is mounted below the pool surface and somehow convection looping could be initiated. That is a good possibility but would involve far more plumbing - and larger pipes to get the flow going. Perhaps a project for this fall to keep the pool from freezing. :eusa_thin

BTW, the pool is a 29' x 4.5' above ground surrounded by a deck. It holds 18,000 gallons of water (DAMHIKT). Last night's 1" rainstorm dropped the temp to 84 degrees and it was back up to 88 degrees 2 hours ago. I think I'll go swimmin'! :eusa_danc

 

[Glennbear]

I was reluctant to use copper because of the corrosive nature of chlorinated pool water. I already had some copper radiator tubes from the hydronic baseboard heating system removed from my former home, but felt they wouldn't last. Most components used around pools today are either plastic or stainless steel.

You are 100% correct Dennis, my second career was as the manager of a college aquatic center and I saw first hand how heated chemical laden pool water eats copper. I try not to think about the time when we lost the core of the heat exchanger and the pool water mixed with the heated water from the campus central steam plant :BangHead: The other thing to be considered is galvanic reaction between copper piping and any disimilar metal in the pool structure or anything in contact with the water such as ladders etc. :wsmile:

 

[CDPeters]

Dennis -

I know this would involve more expense, but...

I saw a project a while back that involved a heat exchange system. The guy built a tank of about 4'x4'x4' out of plywood - a la concrete form style - and lined it inside with pond liner and outside with 2" styrofoam insulation. He then circulated fresh water through the tank and a copper pipe solar collector with a temperature controlled pump to keep the tank water hot. The pool/spa water was then circulated through a big coil of pvc pipe immersed the exchanger box, thereby isolating the copper solar panel piping from the chemical-rich pool/spa water.

Just a thought...

C.

 

[Gotcha6]

Dennis -

I know this would involve more expense, but...

I saw a project a while back that involved a heat exchange system. The guy built a tank of about 4'x4'x4' out of plywood - a la concrete form style - and lined it inside with pond liner and outside with 2" styrofoam insulation. He then circulated fresh water through the tank and a copper pipe solar collector with a temperature controlled pump to keep the tank water hot. The pool/spa water was then circulated through a big coil of pvc pipe immersed the exchanger box, thereby isolating the copper solar panel piping from the chemical-rich pool/spa water.

Just a thought...

C.

2" Styrofoam I got..
Plywood I got.
Treated wood I got.
Pond liner I can get.
Priced any copper lately? :cry_smile
His system uses 2 pumps as well. It could be more efficient, true, but it sounds much more costly to run & build as well. Nonetheless, I'll give it serious thought. :eusa_thin
Thanks.

 

[timf67]

I know stainless isn't cheap, but the added heat transfer ability of metal over plastic may make it worth it for you. Then again, you may get too much heat...:dontknow: