Solar, and SWG

[JamesW]

For a rough estimate, at 2240 rpm, I would estimate the flow as follows.

Filter psi.........flow in gpm.
5...........................60
6...........................50
7...........................45
8...........................30
9...........................15

Note: Very rough estimate.

 

[Dirk]

I dont. I barely know what a hose looks like.

No worries. If you like, you can take a few good pics of your equipment pad and post them. We'll take a look for you.

 

[carnivalday]

For a rough estimate, at 2240 rpm, I would estimate the flow as follows.

Filter psi.........flow in gpm.
5...........................60
6...........................50
7...........................45
8...........................30
9...........................15

Note: Very rough estimate.

Okay! So when I set my RPMs to 2200 and it was at 8 psi, then I had (approx, I know, but better than my dart board approach) 30 gpm, which is actually exactly the flow Im looking for.

So at 2240 RPMs, if my psi is changing, what does that mean? Does that mean a cartridge clean is due?

 

[Dirk]

So at 2240 RPMs, if my psi is changing, what does that mean? Does that mean a cartridge clean is due?

I better let someone else take on those questions, but I just wanted to continue my sales pitch! This is one way I continue to use my FlowVis. I was prepared to eat the cost of the thing for just one reading, because I figured once it told me my system's flow rate, I'd set the RPMs for my panels and that'd be it. But what I didn't realize at the time, is that my flow rate changes throughout the year because of my filter! (Which I so far have only cleaned once a year.) As my filter fills up, my flow rate drops. So I periodically check my FlowVis, and goose the pump's RPMs as need to maintain the 40GPH for the panels. Flow also affects my SWG and my suction-side vacuum, so I use the FlowVis to help me optimize those systems in addition to the solar system. And I do that several times a year. (That's what I meant by getting continued value from the Vis.) You can approximate all this with the pressure gauge, as James is teaching you, but with the Vis I don't have to guess.

 

[mas985]

So at 2240 RPMs, if my psi is changing, what does that mean? Does that mean a cartridge clean is due?

Changing over a long period of time or fluctuation second to second? The former would be the filter getting dirty while the latter could be that the panels still are not fully primed.

And to your previous question about over pressure, the panels are rated to over 200 PSI with an operating pressure of 90 PSI so no where near the limit.

 

[Tres Gatos]

Another thing you can try is get an infrared thermometer and check temperatures of the input and output pipes to panels. It should be about 4 degrees difference for optimal efficiency. Then dial in your rpm from there and you won't have to guess GPH.

 

[Dirk]

Another thing you can try is get an infrared thermometer and check temperatures of the input and output pipes to panels. It should be about 4 degrees difference for optimal efficiency. Then dial in your rpm from there and you won't have to guess GPH.

Interesting. For that matter, couldn't you shove the tip of a thermometer into a return, and then compare that to the water temp mid pool? Though I think it's not just about temp. You also have to have the proper volume of water exchange. If you don't have enough warmer water exchanging with cooler pool water, the temp differential might be right, but you won't actually make a significant change in your pool. Something like that. That's why I was inclined to accept the panel manufacturer's spec (which for my panels was in GPM, not temperature differential).

 

[carnivalday]

Changing over a long period of time or fluctuation second to second? The former would be the filter getting dirty while the latter could be that the panels still are not fully primed.

And to your previous question about over pressure, the panels are rated to over 200 PSI with an operating pressure of 90 PSI so no where near the limit.

I meant over a period of time. I thought there had to be a reason for your chart having the PSI being a moveable number. You have the PSI going up, as the GPM is going down, which would indicate to me that the pump is working harder to do less, so its likely the filter?

And Dirk, I did look at the page for the FloVis. Certainly looks like something I might want to add in the future, tho it looks a little complicated for me right now. Do definitely appreciate the sales pitch. I dont know what I dont know, and I didnt know about that FloVis.

Thanks everyone for contributing here. I definitely feel like I got a lot accomplished today with my pool education.

 

[JamesW]

https://aquamagazine.com/service/how-to-read-pump-system-curves.html

See this reference.

For every configuration of the system, you have a "system curve" that describes how the total "head" (pressure) changes vs. the flow.

In your pump manual, there's a pump curve that describes how the flow changes at different "head" (pressure).

When you graph both on the same chart, the lines intersect to show the operating points.

So, it's a multivariable thing that makes it difficult to understand.

Mainly you just need to increase the speed enough to activate the cell flow sensor and to be able to feel good flow from the returns.

 

[carnivalday]

James, it is definitely difficult for me to understand. I do best with parameters to stay between the rails. I know its not always that easy of an explanation, but I think I have enough info to be able to work with my system. I need to understand the "why" without having to get too deep into verbiage that is over my head. I think I hit that mark today.

 

[carnivalday]

So I decided to conduct a scientific experiment pertaining to my solar heater today. Water is about 66, still too cold for me. But its so darn nice outside, so I sat on the edge and dangled my legs, not noticing I was dangling next to a return. Ooooh, nice pressure.....and warm water!!!! Woot, its working!

 

[mas985]

If the water is more than a few degrees warmer than the pool water, it could mean the flow rate through the panels is too low. For optimal efficiency, outlet temps should be no more than about 3 degrees warmer than inlet temps.

 

[carnivalday]

It didnt feel a lot warmer; it just felt a bit warmer, like when I dangled my foot over it, I had to wait a few seconds to feel it was actually warmer than the pool water.