VS Pump speed

KevinBond

Well-known member
May 7, 2021
101
Kitchener, Ontario, Canada
Pool Size
71000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I took the check valve off again but couldn't see a part number or any other markings anywhere. I definitely see how it's restricting flow though, only a small area for water to get through around the center.
 

JamesW

TFP Expert
Mar 2, 2011
27,187
I would get rid of the check valve or at least replace it with a Jandy check valve.

That check valve has too much head loss.

The formula for your system curve is about:

H = 0.026F^2

H = Head loss in feet.

F = Flow in GPM.


That is still about 3 times higher than it should be.

1623020934420.png

KevinBond Update system curve.jpg

1623021680543.png
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
43,734
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
JamesW - can the guts be pulled out of the CV?
 

JamesW

TFP Expert
Mar 2, 2011
27,187
I think that the valve can be disassembled and the guts removed.

Remove the pins as shown in the video.

Pin at arrow.


Praher Check Valve pin.jpg
 
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JamesW

TFP Expert
Mar 2, 2011
27,187
As you can see from the catalog, the check valve spring can be anywhere from 1/4 psi to 10 psi depending on the model number.

Remove the guts and see if that helps.

Check the heater internal bypass and the thermal regulator.

If you look into the heater inlet, you can see the spring part of the internal bypass.

If you push down on the spring part, you can see the valve part going into the part where the thermal regulator goes.


 
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JamesW

TFP Expert
Mar 2, 2011
27,187
Part 8 is the internal bypass.

If you look in the inlet (top arrow), you can see the spring and plunger assembly.

If you remove the plug (#19) and the thermal regulator (#15 (see video)), and look in the hole (bottom arrow), you can see the flat disc that goes to the internal bypass.

Part #14 can be removed to get a better look at the internal bypass.

I suspect that there might be debris in the bypass check valve.

These heaters are horrible as far as flow efficiency.

They really need to fix this.

It's ridiculous that all of the flow has to go through the tiny opening.
1623025611504.png
 
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KevinBond

Well-known member
May 7, 2021
101
Kitchener, Ontario, Canada
Pool Size
71000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Ok, I got the guts out of the CV:
PXL_20210607_141651799.jpg
Still couldn't find a part/model number...

Here are the updated numbers with the guts removed. Didn't really make much of a difference...

RPMFilter PSIPump PSIGPM
15004712
17256919
192581225
2350131737
2730192446
3110243055
3450293762

Not sure if this sheds any light on the situation but here's the numbers when the filter is in "recirculate" (and CV guts removed):

RPMFilter PSIPump PSIGPM
15004718
17254928
192561137
2350101750
2730142361
3110182970

Check the heater internal bypass and the thermal regulator.
This looks quite a bit more involved. I'll have to wait a couple days to try this. Anything in particular that I'm looking for? I mentioned some rattling coming from the heater near the inlet/outlet. Does that seem like it could be a problem? It isn't loud but it is constant.
 

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JamesW

TFP Expert
Mar 2, 2011
27,187
Undo the two unions at the arrows and look inside the heater inlet to see if the internal bypass looks OK.

InkedKevin Bond system_LI.jpg

If you look into the heater inlet, you should see the internal bypass.

If You push on #1, you should be able to see the disc #2 moving in the thermal regulator hole.

1623085327250.png
The black arrow below is the inlet. You can actually unscrew the inlet piece that the black arrow points to if necessary.

The red arrow is the thermal regulator hole where you should be able to see the internal bypass disc as you push on the other side. Just remove the plug and the thermal regulator.
1623085156924.png
 
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JamesW

TFP Expert
Mar 2, 2011
27,187
This looks better and the new graph is about H = 0.015F^2.

The filter is creating some head loss.

The suction might have an issue.

For the below set of numbers, did you get the reading at full flow at 3,450 rpm?

1623086964447.png


1623086933489.png


Maybe get a vacuum gauge for the suction and a flow meter.

You can put the flow meter on the vertical pipe between the filter and the heater.

You can put the vacuum gauge on the pump strainer drain plug hole.

Just be sure not to overtighten the gauge or you could crack the threaded hole.

BlueWhite flow meter..jpg






1623087679258.png
 

KevinBond

Well-known member
May 7, 2021
101
Kitchener, Ontario, Canada
Pool Size
71000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
BTW, there were no pins in the threads (those were just empty holes). I was able to pop off the end with a flat-head screwdriver (red arrow below) to remove the guts:
PXL_20210606_145213164.jpg
All my ball valves are Praher (they have clear part numbers) so it stands to reason the CV is also Praher as you surmised. I just don't know what model...
 

JamesW

TFP Expert
Mar 2, 2011
27,187
Ok, the spring does not look super strong.

So, it might be a 1/4 psi check valve.

Removing the parts did not seem to do much anyway.

Maybe an issue with the heater, filter or suction.
 

KevinBond

Well-known member
May 7, 2021
101
Kitchener, Ontario, Canada
Pool Size
71000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
This looks better and the new graph is about H = 0.015F^2.
You mean with the filter in recirculate? I would love if I could get the pump to run at this rate when in filter-mode! So quiet!
The suction might have an issue.
Would that mean something is blocking/restricting the suction pipe(s)?
The filter is creating some head loss.
Could it be an issue with the multi-port valve?
For the below set of numbers, did you get the reading at full flow at 3,450 rpm?
I didn't as I wasn't sure the high GPM would cause any problems. I can get those values if it's there's no issue.
Maybe get a vacuum gauge for the suction and a flow meter.
I would install these before the pump?
InkedKevin Bond system_LI.jpg
 

JamesW

TFP Expert
Mar 2, 2011
27,187
The gauge (G) can go at the pump front drain plug hole if it will screw in. It's close to the ground and the gauge might hit the ground as you try to screw it in. You can undo the pump unions to lift the pump to install the vacuum gauge. Don't overtighten the gauge.

If you install a gauge, protect it from getting stepped on as that could crack the pump at the hole if someone steps on the gauge.

The flowmeter (F) can go on the vertical pipe at the F.

InkedKevin Bond system 55_LI.jpg
 
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JamesW

TFP Expert
Mar 2, 2011
27,187
If the vacuum gauge is 10 inches of mercury or less, that's good.

If it's over 10 inches of mercury, that's bad and might indicate a blocked suction.

20 inches of mercury, or higher, puts the pump in danger of cavitating.

3110182970

At 3,110 rpm, the total system pressure minus the filter pressure indicates a possible 11 psi on the suction, which is 22 inches of mercury or 25 feet of head.

The pump numbers are not super reliable because they are not from actual measurements. They are from calculations from the power used.

We would need actual vacuum gauge measurements from a vacuum gauge and flow measurements from a flowmeter. to be sure.

1623093488855.png
 
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needsajet

TFP Expert
LifeTime Supporter
Jan 4, 2016
4,949
Sydney, NSW, Australia
Pool Size
44000
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Plaster
Chlorine
Salt Water Generator
Yayyy, from JamesW's experience, we finally learned how the pump knows it's flow :). Sounds like the pump's brainbox converts power draw to an expected PSI, and therefore flow, knowing its RPM.

And we've also learned from your very helpful testing that the pump is wrong in its own expression of PSI by about 30%, assuming your pressure gauge is likely to be close to correct, which I think is a reasonable assumption. You would only expect that to be lower by a small fraction of one PSI (pressure loss in pipe from pump to multiport), if the pump's brain was correct. (I'm also assuming your pressure gauge reads zero when the system is off, and that it's reasonably new).

Point being that if your pump is calculating pressure higher than it actually is, it's also calculating flow that's lower than it actually is. It would respond by spinning faster to achieve the flow rate it's been asked to achieve by way of your flow setting.

So if it were mine, I'd turn that gobbledygook off, and run it based on RPM. There's a strong possibility that there's no practical problem here at all (other than that intelliflo VF pumps aren't fantastic at calculating their flow rate).

Alternately, you could set flow rates low. A possible problem with that is the minimum 20 GPM in the settings, which might truly be delivering more like 25-27 GPM, more than you need for the SWCG. Conversely 20 GPM (the pump believes itself to be) is a nice low end safety limit for your heater, which is spec'd at a minimum flow of 25 GPM.

I have huge respect for the posters and information you're getting, and if you're enjoying the exploration and don't mind some cost, that's great too, because the rest of us following along are learning heaps here.

Your suction will be around 5 inHg higher than average circumstances because of the 6 foot lift (IIRC) from pool to pump.
 

JamesW

TFP Expert
Mar 2, 2011
27,187
pump is wrong in its own expression of PSI by about 30%, assuming your pressure gauge is likely to be close to correct, which I think is a reasonable assumption.
The filter gauge only records the return side.

So, you have to add the suction side to make up the difference.

We would need a vacuum gauge reading to be sure.

With the 6 foot lift to the equipment pad and then about 3 more feet to the pressure gauge, you have to add 4 psi to the pressure gauge.

So, the filter pressure is really 22 psi, which leaves 7 psi for the suction.

So, not as bad as I thought on the suction.

7 psi is (14 inches of Hg) or 16 feet of dynamic head loss, which is still too high.

Even if you have 70 gpm going through 100 feet of 2" PVC pipe, the dynamic head loss should not be more than 8 feet.

If the 70 gpm is going through (2) 2" PVC pipes. the head loss is only 2.2 feet of head.

So, possibly at least twice as much dynamic head loss as expected.

With the known lift, the suction pipe should have been upsized to compensate.

The total static and dynamic is still 22 inches of mercury or 25 feet of head.

1623110294862.png
 

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