solar pool heater - optimal feeding pipe diameter?

[bubbahotep]

hi,

i have built a solar pool heater similar to the sprinkler coil approach.

http://rimstar.org/renewnrg/solar_pool_heater_diy_fp.htm

I use a separate pump which has a 1 1/4 outlet thread the pressure gauge in the pump says 50 psi. From there I use a 5/8 garden hose to my lateral feeder pipe that has 1/2 (0.5) just as the 4 sprinkler tube coils. the outlet is also 1/2 going into another garden hose and into the pool.

I get 7.5 gal/min and pool is heating up nicely. nevertheless I was wondering if the performance would increase if the lateral feeder pipes were 1 1/4 or 1 1/2 as well.

securedownload-large.jpg

would anyone know if a bigger diameter on the feeding pipes would be better ?

[Mike90250]

.......would anyone know if a bigger diameter on the feeding pipes would be better ?

Bigger is ALWAYS better.
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Seriously, larger flows better with less load on the pump. You want more water flowing, at lower temps, and you get the most gain, if you can feel the water is warmer, it is moving too slow, and re-radiates heat (loss) you coudl be gaining.

1,000 gallons at + 1 degree warms a pool faster than 50 gallons @ 20 degrees.

[russ]

Look at the header in the Rimstar photos - the size is done well - the header has to be larger to get reasonable distribution between the different coils.

[bubbahotep]

Seriously, larger flows better with less load on the pump. You want more water flowing, at lower temps, and you get the most gain, if you can feel the water is warmer, it is moving too slow, and re-radiates heat (loss) you coudl be gaining.

Thanks, thats a start. So water coming out of the system is 10 degrees F warmer. I dont really want to change the coils, as they were a pain to assemble but I could get new feeder pipes from the pump to the 4 coils.

1. Would changing the feeder pipes to 1 1/2 inch make a difference to the whole system, if the 4 coils remain at 0.5 inch ?
2. The outlet thread at the pump is 1 1/4. Rimstar says, they used the same diameter as the pump eg 1 1/2 to 1 1/2, so in my case that would be 1 1/4 to 1 1/4. Should I stay at 1 1/4 for the feeder pipes or would it be better to increase the feeder pipe to 1 1/2?

best regards
Bubba

[russ]

Only for -

1) pressure drop - a larger line will have less pressure srop

2) more equal distibution between the coils

[bubbahotep]

okodoki thanks for the clarificatrion! on my way to home depot !

Ill take a baseline and post the difference in performance from 1/2 inch pipes to 1 1/4.

[bubbahotep]

actually one more question.

If the diameter of the output hole in my pump is 3/4 inch, does it makes sense to extend the diameter of the following pipe to 1 1/2 or should I remain on the pump diameter ?

[Mike90250]

Longer runs need larger pipe to keep flow resistance down.

[bubbahotep]

pipe diameter

Hi,

I have setup a 3 500ft coil solar pool heater and it works nicely. I want to add more 3 more coils. I have a 1 hp shallow well jet pump.
While doing so I was wondering about the following questions:

1. feeder pipe diameter
Does it change the characteristics (flow speed, pressure) of the setup if I would use larger diameter feeder pipe for input and output pipe? Even though my pump threads are smaller (1.25 into pump, 1" out of pump) ? If so how would it change? I am currently using 3/4" pipe in and out.

2. I have a sucktion sump pump.
Does it make a difference if I put the pump at the bottom and pump the water up versus if i would place it on the roof and suck the water up?

Here is a schematic of my setup and a page from the manual.

Thanks in advance for the help!
pool heater setup.jpg
pump manual 1-large.jpg
pump manual 1-large.jpg

[inetdog]

2. I have a sucktion sump pump.
Does it make a difference if I put the pump at the bottom and pump the water up versus if i would place it on the roof and suck the water up?

It makes a difference if the distance from the pool surface to the place where the pump is located is more than the maximum suction head of the pump.
There can also be problems with sucking if the pump loses prime. It does not pump air very well.

[russ]

For pressure drop http://www.pipeflowcalculations.com/pressuredrop/

That calculator can help you with pipe sizes.

Your pump will have a specification on it - it will state how much head it can develop - also how far you can lift water to the inlet.

Sump pumps normally don't have much capability to lift water to the pump inlet.

[harrold]

Setup

Thanks for this setup! Very usefull!

Hi,

I have setup a 3 500ft coil solar pool heater and it works nicely. I want to add more 3 more coils. I have a 1 hp shallow well jet pump.
While doing so I was wondering about the following questions:

1. feeder pipe diameter
Does it change the characteristics (flow speed, pressure) of the setup if I would use larger diameter feeder pipe for input and output pipe? Even though my pump threads are smaller (1.25 into pump, 1" out of pump) ? If so how would it change? I am currently using 3/4" pipe in and out.

2. I have a sucktion sump pump.
Does it make a difference if I put the pump at the bottom and pump the water up versus if i would place it on the roof and suck the water up?

Here is a schematic of my setup and a page from the manual.

Thanks in advance for the help!
[ATTACH=CONFIG]2832[/ATTACH]
[ATTACH=CONFIG]2833[/ATTACH]
[ATTACH=CONFIG]2834[/ATTACH]