Help setting pump speed

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Ryano2121

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Oct 2, 2014
72
San Marcos, Ca
I have a new to me IG plaster pool 13,000 gallons. I have 6 10x4 solar panels on the SW facing roof in the San Diego area. Pipes for the solar are 2.5". Pump is 1' above the pool and the solar panels are 16' above the pump. I just had an Intellifo VS pump installed, replacing a single speed pump. There are 2 drains on the bottom, one skimmer, 3 outlets, and a waterfall.

Prior to replacing the pump, the solar alone kept the pool around 85 on average. After installation, the pool is now at 74. Average temperature at my house has been mid 80s. Solar noon is 12:37.

The installer set the pump at 1600 rpm from 9-5 because that was needed to keep the vacuum running, and 2200 rpm from 5-8. At the low speed I cannot discern any temperature gain between the pool and the water entering the pool at any time of day. The solar controller says it's heating and the valve is in the correct position.

After a lot of reading, I understand that higher flow rates provide more efficient solar heating. Using the pump chart and .05 gpm/sqft for the solar panels, 240 gpm/sqft I set the pump to run at 1900 rpm from 9-1, then at 2250 rpm from 1-4 when the sun most directly hits the panels, and back to 1900 from 4-7. I think this should turn the pool once in 24 hrs.

This is the first day it will run fully on this schedule.

Does this seem like a good schedule to try to get the pool back up to mid 80s (or higher)?

Thank you!
 
:wave: Welcome to TFP!!!

Turn over is meaningless. Read this and ask questions if you still have them: Determine Pump Run Time
I don't think you should need to run the pump nearly that long.

I think your estimate of required flow rate is a bit off. I though most panels were looking for closer to 0.1 GPM per sqft of panel.
 
1900 RPM may not be fast enough to generate enough pressure to keep the VRV closed. Normally, for a two story install, you will need at least 8-10 PSI at the filter. Do you know where the VRV is installed, before or after the panels?

Also, you need at least 40-45 GPM for priming so when the panels turn on, does the pump ramp up to prime the panels?
 
I don't know where the vrv is installed. The pump does prime.

At 1900 I have 10psi.

Just feeling the water at different rpms it feels the warmest at 2000 (12psi). Going from 2200 to 2000 made a noticeable difference in temperature. I think at the higher speed it doesn't have enough time to heat. At 1800 the water gets noticeably cooler.

So I'm thinking 2000 is the sweet spot for solar efficiency. Sounds like if I run at that speed from 12-5 when it's hottest, I will have enough circulation and heat the water the most.
 
That is a common misconception. Solar heating works better at higher flow rates. You will add more heat to your pool by raising a lot of water by a couple degrees than less water by more degrees.

The solar panels should only raise the temp of the water by ~2 degrees. If you can feel the panels and they are warm, then you are not running enough water through them. The panels should be cool to the touch.
 
Yeah, I read about flow rates before I posted. It would seem that at some point the water would flow too fast to heat efficiently. My understanding is that low flow rates result in loss of heat to the environment. I'm going to give it a few days and see what the temp does.
 
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