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Hello All, I’ve spent 2 weeks trying to figure out what kind of pump I should purchase and I’m more confused now than when I started. I’ve built a solar heater for my pool using 1/2” black thin wall tubing. I have about 700 feet of tubing on the roof of my house. Currently I’ve been using a sump pump placed inside the pool to pump the water up to the roof ( 18 feet straight up ) and thru the 700 feet of tube and back to the pool. Using the sump pump( 700 watts) I’m getting a flow rate of 100 gallons per hour and an excellent temperature output of over 100 degrees. I’m incredibly pleased with the performance and can heat my pool to 85 degrees in just 2 days of sunshine.

The problem: 1. The sump pump is expensive to run. 2. My pool pump is not powerful enough to use as a circulation pump. 3. I have to remove the sump pump from the pool every time we want to swim.

The system I’m attempting to creat is completely independent from the pool pump. I’ve attempted to calculate the head height and have confused myself completely. I am looking for a pump that is efficient, sits below the water level outside the pool( above ground pool), can pump the water 18 feet straight up and then thru 700’ of 1/2” hose with a minimum output flow rate of 100 gallons an hour. The flow rate could be more because I can use a bypass to control both flow and volume.
I would also eventually like to expand my system with more hose or use parallel hoses and increase the flow rate.
I would really like to learn how to calculate the head height of my system. Could someone help me learn how to calculate the head height and what type of pumps are best to use.
Thanks for your time.

John
 

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There are several different factors involved in the calculation. We used to do these calculations by hand and used charts in chemical engineering text books to do this.

If you are willing to slightly cheat, here is an on line pump calculator. I have not tested it but it is a commonly used engineering web site.

https://www.engineeringtoolbox.com/pumps-power-d_505.html

Without doing the calculation, the 700 ft of line probably represents just as much of the pressure drop than the 18 ft of height.

This is absolutely going to be a high electricity cost to run. Some pumps are better than others at various flow / pressure conditions.

One thing that might help is to create a closed siphon effect in the tubing.

If the return line is in the water at a depth relatively similar to the pump depth, AND the tube is 100% full with no air, the water coming back down will off set "some" of the effect of pumping it up. It's not perpetual motion - there are losses, but it can off set "some" of the power used to lift the water up onto the roof.

Nothing can off set the loss of pumping through 700 ft of line.
 

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Cost wise, 700 watts is close enough to 1 kW to use it as a cost basis.

In this area, that is about $0.25 / hr to operate.

It is actually a perfect example of when a solar PV system is useful for powering a load.

Since solar PV panels in the real world make about 1/2 of their rating, you will need 2x what you think, so 2 x 700 watts is about 1500 watts.

If you want power all day, then it might require 1500 watts of panels on each roof direction to run.

1500 watts is about 5 panels @ $250 / each. Roof mounting hardware cost about the same as panels.

Battery + inverter + solar charge controller ~ $2-3K.
 

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Another possible path for you is an open loop system.

The city water pressure is sufficient to push water through your system and into the pool.

For very little hardware cost, you could just use an outside faucet and feed water into that tube - run it through the coil - and then dump it into the pool.

Adjust the flow rate with a valve until you are happy with the flow and water temperature. Maybe 25 gallon an hour ish.

You will have to do your own estimate of the two approaches of chemical cost vs electrical cost.
 

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Hello All, I’ve spent 2 weeks trying to figure out what kind of pump I should purchase and I’m more confused now than when I started. I’ve built a solar heater for my pool using 1/2” black thin wall tubing. I have about 700 feet of tubing on the roof of my house. Currently I’ve been using a sump pump placed inside the pool to pump the water up to the roof ( 18 feet straight up ) and thru the 700 feet of tube and back to the pool. Using the sump pump( 700 watts) I’m getting a flow rate of 100 gallons per hour and an excellent temperature output of over 100 degrees. I’m incredibly pleased with the performance and can heat my pool to 85 degrees in just 2 days of sunshine.

The problem: 1. The sump pump is expensive to run. 2. My pool pump is not powerful enough to use as a circulation pump. 3. I have to remove the sump pump from the pool every time we want to swim.

The system I’m attempting to creat is completely independent from the pool pump. I’ve attempted to calculate the head height and have confused myself completely. I am looking for a pump that is efficient, sits below the water level outside the pool( above ground pool), can pump the water 18 feet straight up and then thru 700’ of 1/2” hose with a minimum output flow rate of 100 gallons an hour. The flow rate could be more because I can use a bypass to control both flow and volume.
I would also eventually like to expand my system with more hose or use parallel hoses and increase the flow rate.
I would really like to learn how to calculate the head height of my system. Could someone help me learn how to calculate the head height and what type of pumps are best to use.
Thanks for your time.

John
John,

I've been searching around for the same goal. I tried quite a few different ideas but finally settled on a simple design that works great!

First off, I tried the sump pump idea too, I found the same thing you did. They work great but you need an pump that's far larger than practical. What I found is that you need to search for a "booster pump" instead of just searching for a water pump.

Here's what I settled on: https://smile.amazon.com/gp/product/B07XXVQLB4/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

This pump was cheap at $60 and did a perfect job. I'm a little crazy so I did more testing than was necessary.

Here's my setup:
17 foot round above ground pool. 5/8 landscape black landscape tubing that starts from the bottom drain port of the pool with a garden hose 3/4" connection. I used about 5 feet of tubing then mounted my pump vertically to a nearby tree. The total head height is only 8 feet in my case though, so you may need the next strongest booster pump but I'm not sure on that. I wrapped the tubing to the backside of my roof to a flat area. Total length of tubing used is about 1200 feet! To start my pool was 78 degrees and the water output from my heater setup was 110 degrees, this was on a 95 degree temperature day. The output of the heater was dropped right back into the skimmer/filter of the pool.

More of the technical's:
Tested amperage draw on the pumps highest speed to be 0.793 amps at 120 vac. This equals right at 95 watts.
I hit the Tier 2 pricing for PGE in California and the price/Kwatt is 30.67 cents.
I used a digital timer ($20) to start the pump at 11:00 am and stop at 6:00 pm, 7 hours run time.
I calculated this heater to run 7 hours per day for 30 days should cost $6.11. That's awesome!!
I performed a one gallon fill test and it took 56 seconds. This is equal to 64.28 gallons per hour, which is 450 gallons pumped through my heater coil each day.
My pool is roughly 7000 gallons so about 6.4% of the pools water is cycled every day.

I really hope this helps you out, I wish I found other posts and forums with this much detail.
The big key for me was finding a pump that did not draw much power and still gave a decent amount of flow.

7867


7868
 

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run a few solar electric panels and do a battery back up for that..
and run a dc stainless steel taco pump or pumps (one for the lift and another for the flow as a booster pump.
use the filter system piping for the pool for the water flow.
and you can add in temperature sensors for heat and cold limits.
pricy at first to setup..
but after your buy the system then the power is free!

I would run larger pipe up to the roof like 1-1/2 id min...
then second pump on top.
then split the flow with a manafold to the multi smaller lines for less resistance in the roof panel heat ex changer pipe or hoses.
then combine for gravity flow back down to the pool filters and another pump to work off the solar there.
 
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