Got my new Intellifo VSF installed today, but flow doesn’t seem right

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Yes, return is 1.5” that has a valve between pool and spa and the spa side has another (closed) manual valve for aerators. The pump is a 011056 IntelliFlo VSF.

I hear you on the tab feeder, but flow is even lower when I put in spa mode (bypassing the tab feeder).
 
Ok. Have you verified the voltage going to the pump while it's running?

The numbers seem off, but I'm not exactly sure how.

I think that I would get a flow meter and vacuum gauge to see if the pump information is accurate.
 
If the voltage was low, it would give an alarm. So, I wouldn't worry too much about that if you're not sure how to do it.

Something is off. I'm not super confident about the pump readings.

Your system is not ideal from a hydraulic point of view. It has excessive restriction.

It's odd that you have a single 1.5" line for the return.

How old is the pool?

I would probably get a flow meter and vacuum gauge to see if the metrics are accurate.

Is the filter pressure gauge working correctly?
 
Pool built in 2001. I have a spare filter pressure gauge that I can swap out tomorrow and check, but the filter gauge is only 1.5 years old. I’ll order a vacuum gauge and look into a flow gauge.

Is the tab feeder the excessive restriction you are referring to, or something else?
 
Full prime means that the pump strainer housing stays full of water.

The system is indicating excessive restriction.

The flow calculation doesn't work well with excessive restriction systems.

So, I suspect that the flow indicated on the display is probably not accurate.

In any case, the system is poorly designed and is creating excessive head loss.

A flow meter and a vacuum gauge would be helpful in figuring out what is really happening.
 
If we can get a vacuum pressure, we can add it to the filter pressure to get a total system pressure and compare it to the system pressure from the pump.

The vacuum reading can help us determine if the restriction is mainly on the return side or if the suction side is also an issue.

We can use the system pressure and the pump curve graph from the manual to calculate the actual flow rate in gpm.

We can use the flow meter to get a more accurate estimate of the actual flow rate in gpm.

We can compare the gpm from the pump, the flow meter and the pump curve to see how well they match up.

The single return seems odd. That's really poor design. Is that how it was originally?

I would get rid of the in-line chlorinator. Those things are nothing but trouble.

I would disassemble and clean the filter grids.

Check the rest of the components for any issues that would create excessive restriction.
 
You have a threeway valve at the discharge of the pump where one goes to a Jandy Energy Filter for a return cleaner.

Is that ever used? If not, I would repurpose it as an additional return if the line is good and not leaking.

You need to reduce the restriction in the system to get good flow without using an excessive amount of power.

An extra return should help.
 

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For reference, with a properly designed system, the numbers should be more like this:

3110 rpm, 55 to 60 feet of head (23.8 to 26.0 psi system pressure), 100 to 110 gpm.

2350 rpm, 30 to 39 feet of head (13.0 to 16.9 psi system pressure), 60 to 86 gpm.

To achieve the 40 gpm target flow rate for the heater, you shouldn't need to go higher than about 1,925 rpm.

I would suggest the following:

1) Replumb the return side.
2) Repurpose the cleaner line as a return.
3) Remove the tab feeder. Maybe switch back to SWG.
4) Install a flow meter between the filter and the heater.
5) Install a pressure gauge between the filter and the heater to determine how much the filter adds to the return pressure vs. everything downstream from the filter.
6) Install a vacuum gauge on the suction side.
7) Make sure that the filter is really clean.
 
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James - Thank you so much for all the help. I am working on the getting the parts you suggest, but I have some more data points to consider (all at 2350rpms):

When I open the suction side valve to pull from both pool and spa at the same time, GPMs go up by only 2 gpm, so thinking both sets of suctions lines are pretty clear.

When I open the return valve to both pool and spa at the same time, GPMs go up by 5 gpms.

When I open the cleaner valve above the pump, GPMs jump by 18-20 GPM

So when I make all three of those adjustments, GPMs on the pump at 2350rpms move from about 32 to 59.

If I put the MPV on recirculate, GPMs increase by about 4 GPMS, so the filter is adding some resistance, but doesn't seem to be adding that much.

Does all of this lead you to any further insights?
 
Based on the new information, I would suspect that maybe the heater is creating excessive restriction or maybe the check valve after the heater has an issue.

Maybe look into the heater inlet and outlet to see if you can see anything.

Check the check valve for proper operation.

I think that the flow readings from the pump are probably not very accurate.
 
You can open the check valve and make sure that the flapper moves smoothly.

When reinstalling the screws, make sure to get the screws in the same threads by rotating the screw counterclockwise until you feel it drop in the thread and then rotate clockwise to tighten. Mark the orientation of the top or note that the arrow should be pointing in the direction of the water flow.

If you cross-thread the female threads, it can strip out the plastic.

When looking in the heater inlet, you should be able to see the spring part of the heater internal bypass.

You can check the thermal regulator to see if it looks ok.

While you have the thermal regulator out, you can check the disc part of the internal bypass by looking in the hole and up where it lines up with the spring part.



Sometimes the internal bypass can break loose and cause problems. Or, it can get clogged.
 
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Make sure that the power to the pump is off. You don't want it to turn on by itself by a timer and make a big mess.

If you have to shift the heater to look in the inlet and outlet, you might have to disconnect the gas line at the union. There should be a valve by the union you can close while you have the union open.

Has the heater been working properly recently?
 
Checked the check valve and it seems to be in good working order.
On the heater, every couple of minutes, I could some rattling/gurgling type sound - sounded like it was coming from the outflow side, but couldn’t tell. Is that normal?

Also, ran the heater at 2000 rpms and it had no problem for 10 mins (despite the pump saying it was 28gpm.
 

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