Looking for a way to test GPM at each return

[JamesW]

I'm trying to optimize a pump schedules tailored to each pool.

Make sure that the flow triggers the SWG flow switch to produce chlorine and verify that the weirs are skimming properly.

The exact flow is not critical.

Longer runs at lower speeds are more efficient than shorter runs at faster speeds.

The optimum efficiency is running 24/7 at very slow speed as long as the weirs work and the SWGs works.

Other than that, the flow should only be increased to meet a need such as a flow rate required for a heater.

Automation should be able to increase pump speed on Call-for-Heat.

 

[sorpasorpa]

• Filter: Low speed is better for filtering. Filter long enough so you are happy with the water.

Again this information is super vague for filtering. What metric are we measuring speed with GPM? What is the optimal speed for filtering

Make sure that the flow triggers the SWG flow switch to produce chlorine and verify that the weirs are skimming properly.

The exact flow is not critical.

Longer runs at lower speeds are more efficient than shorter runs at faster speeds.

The optimum efficiency is running 24/7 at very slow speed as long as the weirs work and the SWGs works.

Other than that, the flow should only be increased to meet a need such as a flow rate required for a heater.

Automation should be able to increase pump speed on Call-for-Heat.

I'm familiar with all this information and currently implementing it but I'm trying to get more specific / optimal. What do you consider a very slow speed and how do you measure it?

 

[JamesW]

What do you consider a very slow speed and how do you measure it?

Make sure that the flow triggers the SWG flow switch to produce chlorine and verify that the weirs are skimming properly.

The exact flow is not critical.

As long as the flow serves the functions of allowing the SWG to operate and the weirs are skimming effectively, then the flow is sufficient.

Knowing the exact flow does not really help that much unless you feel like there is a problem like clogged lines.

 

[JamesW]

You could probably get flow meters with a threaded adaptors and screw them into the returns to measure flow if you really want to know.

 

[mknauss]

You would need a flowmeter screwed into all the returns at the same time to balance the system. And the overall flow rate would be lower than without the flow meters as the flow meter has resistance to flow.

 

[JamesW]

https://www.h2flow.net/s/FlowVis-Head-Loss-Data-R10.pdf

https://static1.squarespace.com/static/6054f4b7f30c7f1e91e1f2e9/t/64234e3bf8631f21bbe21b47/1680035390691/FlowVis-Head+Loss+Data+R1.0.pdf

FlowVis flow meter — H2Flow Controls

FlowVis flow meters are a revolution in reliable flow measurement. With unrivaled average accuracy, greater installation flexibility, and more NSF 50 certified models than any other brand, it’s easy to see why FlowVis® is a brand of flow meter you can put your trust in.

www.h2flow.net

 

[sorpasorpa]

As long as the flow serves the functions of allowing the SWG to operate and the weirs are skimming effectively, then the flow is sufficient.

So you're saying the RPMs that the SWG functions at is the optimal slow speed to be running the filter on 24/7. What RPM would you set without a SWG?

You could probably get flow meters with a threaded adaptors and screw them into the returns to measure flow if you really want to know.


View attachment 642427

I think I do want to do this. My biggest concern is that this type of flow meter doesn't have the resolution I'm looking for since the GPM would be very low at each return and I don't think it reads under 10 GPM. I'm currently looking into small flowmeters used on hose adapters.

You would need a flowmeter screwed into all the returns at the same time to balance the system. And the overall flow rate would be lower than without the flow meters as the flow meter has resistance to flow.

That's the plan. I would take each reading and add them up for a total. The flow meters would add resistance since that's how they measure flow but I'm not sure why this is an issue. Care to elaborate?

 

[mknauss]

Once you take the flowmeters off, the overall rate would increase. I suppose that gives you some error range to work with so may not be a big deal.

If you do not have a SWCG, minimum flow rate is that which will skim the surface of the pool. If there is an erosion tablet feeder involved, then that complicates things as they typically need high flow rates to erode the tablets sufficiently.

 

[JamesW]

So you're saying the RPMs that the SWG functions at is the optimal slow speed to be running the filter on 24/7. What RPM would you set without a SWG?

With no SWG, set based on skimmer function.

As long as the skimmer or skimmers are working with visible action, the flow is ok.

The flow meters would add resistance since that's how they measure flow but I'm not sure why this is an issue.

Resistance lowers flow, so you have to calculated what the flow would be without the added resistance of the flow meters.

The added head loss is not too bad based on the published data.

 

[Newdude]

Do you think it's a bad idea to try to optimize a pool systems efficiency?

You are trying to set a standard where the environment is variable. The falling debris and wind can change by the hour, much less the day or month of the season. You adapt on the fly, or you target the maximum filtering needed and the rest of the season is covered by default.

But then youre wasting energy with excessive pump runtime when its not needed.

Most of us here split the difference with low RPM 24/7 runtime. We pick just high enough to skim and run the SWG, then bump it for heating, cleaning, etc. Most of the time its enough. If the spring/fall is dumping tons of dust and debris, we might need to increase the RPM temporarily.

 

[JamesW]

For example, if you have 2 returns and each has 50 gpm, then the total flow is 100 gpm and the flow meters add about 2.9 feet of head loss.

If we lower the head loss by 2.9 feet, the flow goes from 100 to about 106 GPM.

The error is higher for lower flows.

 

[sorpasorpa]

For example, if you have 2 returns and each has 50 gpm, then the total flow is 100 gpm and the flow meters add about 2.9 feet of head loss.

If we lower the head loss by 2.9 feet, the flow goes from 100 to about 106 GPM.

The error is higher for lower flows.

View attachment 642437

I see what you mean. For some reason I was thinking the meters would be calibrated to account for their own resistance and give you a reading without that but that wouldn't make sense.

 

[1poolman1]

I see what you mean. For some reason I was thinking the meters would be calibrated to account for their own resistance and give you a reading without that but that wouldn't make sense.

Why would you want or need to know the flow at each return? Unless each line was valved individually it would be information only and could serve no purpose other than satisfying curiosity or drive you crazy trying to do something about "unbalanced" flow.