Solar pool heater water flow question(s)

[redneck joe]

ahhh... didn't come across that tidbit in my middle of the night researching. Thanks.

Going to bury the lines tomorrow.

 

[redneck joe]

here is the view from my office. note the shade - this was about 1500. at this time the shade is moving off the area but the (out of view) deck has enough to compensate for. I will also be putting curtains around it to help block sun as well.

 

[redneck joe]

Thinking 100 foot or so of pipe. Could fit way more. Maybe a dual system so in the colder months i can push more thru the system for more heat gain.

Thoughts?

 

[redneck joe]

Or go on the higher side of length and regulate with flow rate and time on?

 

[redneck joe]

laid out the pattern for under the cabana. The sides will be different. All used pavers I've bought cheap last 10 years or so and all slightly diff thicknesses.

 

[redneck joe]

12 x 8 shade footprint. The close side (west) will get curtain as will the back so as the day progresses and the shade moves the footprint will get even wider

 

[redneck joe]

doing three pattern of this under the thing - the rest will be a diff pattern. I tried an inside cut twice on the upper right too thin so i'll be replacing. The storm moved in as I was taking the pics so gave up for the day.

 

[redneck joe]

 

[redneck joe]

and the roof decking is up as of today. Need to paint it, plumbing and roof it now.

 

[redneck joe]

here is what we lifted to the roof structure. Didn't work.

Any guesses as to why?

 

[dingbat]

Couple of thoughts:

Heat transfer in tubes is affected by material, wall thickness, the amount of exposed surface, rate of flow, delta T between outer wall surface tubing and bulk fluid temperature, and whether or not you have laminate or turbulent flow

Quick observations:
The elbows in the collector are causing turbulent flow. Coiling the tubing would create laminate flow which is more efficient at heat transfer

Shadows show the tubing (roof) is not perpendicular to the sun’s rays. A large percentage of the tubing is shaded at any given time. A southern exposure is best

Would have concerns with flow in that tube configuration. Tubing must be full of water to maintain contact with wall to affect heat transfer. Assume you have water going into lowest point, exiting at the highest point to keep the pipe 100% full of water at all times?

Could try putting metal roofing under the tubing to get some heat to the under side of the tubing.

Enclosing the collector and covering with glass of some sort would help raise the temperature of the outer wall of the tubing in relationship the the water outside improving heat transfer

 

[Scott Danforth]

Why not use the solar mats made for pool systems?

 

[redneck joe]

I bought one, sent it back. Leaks and other issues. What i learned there was most are made solid this was all tubes with threaded connection s. Way too many future leak possibilities. Moat others appear to be solid. Welded i guess. In looking for replacement my challenge has been maximising my avail space against standard sizing which appears to be 4' and i have 7' so i lose ~40% avail heating space. Trying to work on that one or thinking soft copper coils.

 

[redneck joe]

Well, just found a site that has add on kits in one foot increment so prob may be solved.

 

[Scott Danforth]

I bought one, sent it back. Leaks and other issues. What i learned there was most are made solid this was all tubes with threaded connection s. Way too many future leak possibilities. Moat others appear to be solid. Welded i guess. In looking for replacement my challenge has been maximising my avail space against standard sizing which appears to be 4' and i have 7' so i lose ~40% avail heating space. Trying to work on that one or thinking soft copper coils.

The ones that are used down here come in widths if 18", 24", 30, 36, 42, 48, 54, 60

Lengths from 4-16 feet

They are just a big rubberized polypropylene molded part (no threaded anything). The main "web" is a bunch of hollow tubes between the headers. 2" id headers with about 15-18 tubers per foot.... But it's all molded as one part. They get clamped together with hose clamps. You can also trim them for custom widths

Companies such as aquatherm, fafco and magen.

 

[garbageguy]

garbageguy - total head and head loss, not sure what you mean and not getting much (that I understand) from the internets. ...

Apologies for delayed reply - those are fluid hydraulics (engineering) terms

After reading thru all this after my original reply, looks like you are getting what is likely more practical info - for you (and me too, learning every day is good)

to answer your question
Total head = (static head+velocity head+pressure head) - head losses. That'll give you a "system curve", then compare that to a "pump curve", and select a pump that will satisfy the system curve in a range where the pump will happily operate. It's an iterative process.

But, since your situation has been addressed many times over the years by others - going thru the rigor of first principles is probably overkill here.

I was looking at it like this starts from first principles, and at that time you had no other replies. At this point you've likely received info that is of more practical help for you. To me, engineering is the practical application of technology - and the user of that term, engineering, gets to decide what is practical, and what is technology.

 

[dingbat]

 

[redneck joe]

Apologies for delayed reply - those are fluid hydraulics (engineering) terms

After reading thru all this after my original reply, looks like you are getting what is likely more practical info - for you (and me too, learning every day is good)

to answer your question
Total head = (static head+velocity head+pressure head) - head losses. That'll give you a "system curve", then compare that to a "pump curve", and select a pump that will satisfy the system curve in a range where the pump will happily operate. It's an iterative process.

But, since your situation has been addressed many times over the years by others - going thru the rigor of first principles is probably overkill here.

I was looking at it like this starts from first principles, and at that time you had no other replies. At this point you've likely received info that is of more practical help for you. To me, engineering is the practical application of technology - and the user of that term, engineering, gets to decide what is practical, and what is technology.

I did have the piping system up and the flow was adequate and I still had valves to close so yes, all good.

 

[redneck joe]

that tubing is very prone to exploding when one forgets to either have pump running in daylight or not draining after use. i did use that for my proof of concept. I've had two friends try it out and it is not a permanent thing to use and in my application i need a product to last many years as well as be more idiot proof.

 

[dingbat]

that tubing is very prone to exploding when one forgets to either have pump running in daylight or not draining after use. i did use that for my proof of concept. I've had two friends try it out and it is not a permanent thing to use and in my application i need a product to last many years as well as be more idiot proof.

Aa I said earlier, the #80, 3/4” HDPE in my system is over 25 years old. No explosions yet….lol