How many feet of tubing do I need

[Mr Tucson]

I realize many experts here mention having at least 50% of surface area in related to the tubes and the platform it is coiled on.
Can anyone give me an idea of how many actual feet of tubing might equate to enough.
I have a 17*22 in ground pool so 375 sq ft aprox and 22,000 gallons.

I have planned to run in parallel 1000' of tubing in 200 feet increments. so essentially 5 coils each on a 4x4 plywood-
but that only equates to 80 sq feet ( 5 * 16 ) if I used 100% of the surface area and I am not, I assume I am using about 75% just based on the square sheet and round coils so I have lots of space not used as well as the center of the sheet.

so please assist if you can. I assumed 1000 feet of coiled tubing done properly might be sufficient. putting an additional 1000 feet or 5 more coils of 200 feet each seems like a great deal of panels to have.

where am I going wrong here or am I over thinking this......

any help is appreciated,

[foo1bar]

I have planned to run in parallel 1000' of tubing in 200 feet increments. so essentially 5 coils each on a 4x4 plywood-

What's the width of the tube?
I'd simply multiply that by 1000' to get effective surface area.
ex.
1" diameter tube: 1" * 1000' = 83.3 square feet.

[Mr Tucson]

What's the width of the tube?
I'd simply multiply that by 1000' to get effective surface area.
ex.
1" diameter tube: 1" * 1000' = 83.3 square feet.

thanks for the reply,

so I am using 1/2 inch tubing.

so all I am going to get with 1000 feet of tubing is less than 50 square feet?
at that ratio I would be needing almost 3000 feel of coils.

is that correct?

[J.P.M.]

I realize many experts here mention having at least 50% of surface area in related to the tubes and the platform it is coiled on.
Can anyone give me an idea of how many actual feet of tubing might equate to enough.
I have a 17*22 in ground pool so 375 sq ft aprox and 22,000 gallons.

I have planned to run in parallel 1000' of tubing in 200 feet increments. so essentially 5 coils each on a 4x4 plywood-
but that only equates to 80 sq feet ( 5 * 16 ) if I used 100% of the surface area and I am not, I assume I am using about 75% just based on the square sheet and round coils so I have lots of space not used as well as the center of the sheet.

so please assist if you can. I assumed 1000 feet of coiled tubing done properly might be sufficient. putting an additional 1000 feet or 5 more coils of 200 feet each seems like a great deal of panels to have.

where am I going wrong here or am I over thinking this......

any help is appreciated,

It isn't the ft. of tubing. It's the projected area of the total tube length that matters. 1 lineal ft. of, say, 3/4" O.D. tube has a projected area of: (.75)*(12)/144 = .0625 ft.^2.

If you have, say, a 20' X 40' pool, and a pool heater area of 50% of the pool surface is a 1st cut approx. for a size, that would mean (20) X (40) X (.50)/.06205 = ~ 6,400 lin. ft. of tubing. Or, ~~ 6400/800 = 8 lin. ft. of 3/4" O.D. tubing for each ft.^2 of pool surface.

Unless I was doing this as a learning experience, I'd buy pool collectors made for the purpose and be done with it. Cleaner, easier, probably better aesthetics, probably more efficient and maybe less expensive.

[foo1bar]

so I am using 1/2 inch tubing.

Is that actual outer diameter?
If not, use the actual outer diameter.
Many things like pipes and tubes have a "nominal" measurement - for example 3/4-inch copper pipe has a OD of .875"

FWIW I have less than 50% of the pool surface area for my pool heater.
I'm sure I'd get the water warmer faster if it was larger.
But it's good enough for what I need.

[Mr Tucson]

Is that actual outer diameter?
But it's good enough for what I need.

Well everyone thanks for the information. I am building a nice structure much like the ones that can be purchased so it will look nice and professional as I have an amazing south facing area right near the pump but I am up to around 1000 combined feet of tubing so while I don't think I will hit the 3000+ mark to be at 50% I will get close to 2000 for now and what is nearing 35%.
with a nice pool cover and in Tucson AZ I hope to have those other benefits to aid in the heating. I have no issues on using my gas heater but if this will reduce costs it will still be a win.
todays high was 85 F degrees and not a cloud in the sky so not bad for the start of November.

So I have another question if this can be answered or possibly explain to me in laymen terms regarding the ambient outside temp with a clear sky and what the heat transfer rate would be in temps at 70, 75 and up. Is there some way to determine when it is just to cold out to have any positive effects on the coils? I realize if the sun is not shining / cloudy it will do nothing but I am wondering on outside temps in the low 70's on a clear day will this still have a decent heat transfer rate?

thanks in advance,

[skeeter_ca]

Well, I have figured out the same numbers as you but as seen by good working examples usually between 4 and 8 panels are sufficient. I am starting with 4 panels with a design that is easily expandable. Hopefully I will know when next summer comes around.

skeeter

[J.P.M.]

Well everyone thanks for the information. I am building a nice structure much like the ones that can be purchased so it will look nice and professional as I have an amazing south facing area right near the pump but I am up to around 1000 combined feet of tubing so while I don't think I will hit the 3000+ mark to be at 50% I will get close to 2000 for now and what is nearing 35%.
with a nice pool cover and in Tucson AZ I hope to have those other benefits to aid in the heating. I have no issues on using my gas heater but if this will reduce costs it will still be a win.
todays high was 85 F degrees and not a cloud in the sky so not bad for the start of November.

So I have another question if this can be answered or possibly explain to me in laymen terms regarding the ambient outside temp with a clear sky and what the heat transfer rate would be in temps at 70, 75 and up. Is there some way to determine when it is just to cold out to have any positive effects on the coils? I realize if the sun is not shining / cloudy it will do nothing but I am wondering on outside temps in the low 70's on a clear day will this still have a decent heat transfer rate?

thanks in advance,

I'll try to be brief. The short answer is maybe, depending on the how accurate an answer you're looking for, but probably less likely as the desired accuracy increases you may be looking for.

One way to look at your question is from what's called an energy balance perspective.

In short, assuming a "steady state" situation, where things are running and not changing too much, what goes into a solar device (water heating panels, etc.) in terms of solar energy, will always equal what comes out of the panels.

Now, what goes in is all the solar energy. What comes out of the panels will be the sum of the useful gain (= how much the water is being heated), and the energy (heat) loss from the panels to the environment, due to the panels probably being warmer than the ambient air and the surrounding structures and the sky. Subtracting the useful output (the energy that goes into the water), from the total input (the solar energy) will be what the loss is from the collector to the environment.

Bottom line: The temperature difference between the ambient and the collector is what increases the loss to the environment. That increase is more or less in direct proportion to that temperature difference between the collector and the evvironment.

Because both the input and the losses are constantly changing, as are the environmental conditions that control the rate of losses per degree as well as the temp. diff. between the collector and the environment, a one size fits all one # answer is not possible with any reasonable degree of numerical accuracy.

SWAG: If the sun is shining and the air temp. is within, say, 10-20 deg. F. (lower) than the pool water temp. or greater, useful heat is probably being collected.

Decent solar pool heaters can operate at ~ 70+ % efficiently under sunny skies when pool temps are somewhere near ambient air temps. A real wild SWAG might be that the efficiency rolls of something like about 5% per deg. F. difference between the pool and the amb. temps., depending on a lot of variables.

[Mr Tucson]

I'll try to be brief. The short answer is maybe, depending on the how accurate an answer you're looking for, but probably less likely as the desired accuracy increases you may be looking for.

.

Well this was perfect information and I realize there are so many variables but this gives me a great view and idea on when to run the system and when to keep it off. I am upgrading my pool equipment this week and primarily my pump to a top end variable speed pump made by Intelliflo so they are going to plumb this with valves for my system.


Thanks for the great info and help on this board.

Mrtucson

[J.P.M.]

Well this was perfect information and I realize there are so many variables but this gives me a great view and idea on when to run the system and when to keep it off. I am upgrading my pool equipment this week and primarily my pump to a top end variable speed pump made by Intelliflo so they are going to plumb this with valves for my system.


Thanks for the great info and help on this board.

Mrtucson

For anything I spewed out that may have been helpful, you're welcome. Hope it continues to be helpful in the future. The big takeaway might be that while reasonable estimates are possible, a good eyeball and some common sense will usually get close and go a long way to probably doing the trick.

Regards,