Pump Basket has air trapped - most of the time.

[Woody007]

What would be the impact of adapters and reducers on the 1.5" pipes going to what looks like a 3" union at the pump on suction and pressure sides?
Would an oversized pump have problems expelling air trapped at the top of the basket?
The air in the pot appears to just be rolling and not leaving. If I shut off the pump, the water level in the basket doesn't change. I've never seen any air enter other than when I've removed the lid for cleaning. It primes in ~30s but just leaves the dome full of air.
Can the pump be too large? Could it be the adapters from 1.5' to the hugh unions at the pump? How many other peoples VSF3 3hp pumps have air trapped in the pot?

 

[mas985]

What would be the impact of adapters and reducers on the 1.5" pipes going to what looks like a 3" union at the pump on suction and pressure sides?

A 1.5" to 3" bushing has about the same head loss as a single 90 elbow which is not much so I don't think that is the issue. But please post some pictures of the entire suction side of the pump and plumbing.

Would an oversized pump have problems expelling air trapped at the top of the basket?

Not if plumbed properly and without any air leaks.

The air in the pot appears to just be rolling and not leaving. If I shut off the pump, the water level in the basket doesn't change. I've never seen any air enter other than when I've removed the lid for cleaning. It primes in ~30s but just leaves the dome full of air.
Can the pump be too large?

Not a VS pump because you can always reduce RPM to make it any size you want.

Could it be the adapters from 1.5' to the hugh unions at the pump?

No. See above.

How many other peoples VSF3 3hp pumps have air trapped in the pot?

Not many. Only those that have air leaks and/or very high head loss.

 

[mas985]

Some additional information that would be useful:

Distance from pool to pump

Pipe size from pool to pump

Number of suctions runs

Filter PSI with pump running at 3450 RPM

Height of filter gauge with respect to water level

 

[Woody007]

Some additional information that would be useful:

Distance from pool to pump ~ 40' from bottom drain. Add another 20' to farthest skimmer

Pipe size from pool to pump 1.5"

Number of suctions runs One to bottom drain, one to both skimmers

Filter PSI with pump running at 3450 RPM 3K is my reference RPM and reads 20 psi

Height of filter gauge with respect to water level Height of Jandy DE filter plus ~18" above pool level

Answers above.
This is a new install. Previous SS Challenger never had any air stuck in basket.
Jandy valve and fittings have been replaced on the input side.
Pictures attached.

 

[sande005]

What happens if you run it with the valve closed so it only pulls from one of the intake lines? Better or worse?
Is the line without the valve from the skimmer? If so, can you plug the skimmer with a rubber stopper/gizmo or other, and see if that changes anything?
Neither can be conclusive that the problem is in one leg or another, but it can give clues.

 

[mas985]

Filter PSI with pump running at 3450 RPM 3K is my reference RPM and reads 20 psi

I know that but it would be more useful to get a benchmark at full speed.

Height of filter gauge with respect to water level Height of Jandy DE filter plus ~18" above pool level

The gauge is at 18" APL or the bottom of the filter is 18" APL? I need to know the level of the actual gauge, not the filter.

 

[Woody007]

What happens if you run it with the valve closed so it only pulls from one of the intake lines? Better or worse?
Is the line without the valve from the skimmer? If so, can you plug the skimmer with a rubber stopper/gizmo or other, and see if that changes anything?
Neither can be conclusive that the problem is in one leg or another, but it can give clues.

No difference if I close the intake to either the skimmers or the bottom drain. Both the skimmer and drain line go through the valve. It doesn't show very well in the picture.

 

[Woody007]

I know that but it would be more useful to get a benchmark at full speed.
The app shows percent of speed, so if 100% is 3450 the gauge reads ~30 psi. That is higher than I ever saw with the single speed by about 8 psi.


The gauge is at 18" APL or the bottom of the filter is 18" APL? I need to know the level of the actual gauge, not the filter.
Bottom of filter is 18" APL. Gauge is on top of 40" filter so approx. 58" from pool level to guage on top of filter.

 

[mas985]

The app shows percent of speed, so if 100% is 3450 the gauge reads ~30 psi. That is higher than I ever saw with the single speed by about 8 psi.

That means the flow rate is much higher with the new pump than it is with the old pump.

Bottom of filter is 18" APL. Gauge is on top of 40" filter so approx. 58" from pool level to guage on top of filter.

So at full speed, flow rate estimate is around 62 GPM which is fairly low for that pump and would suggest fairly high head loss of around 84'. But even so, that is more than enough flow rate to purge the pump basket of air. So if there is still air in the pump basket at full speed, there is an air leak somewhere.

Could you post a picture of the filter gauge at both 3450 RPM and 3000 RPM? There is a bit of a disconnect between the two measurements and it could just be rounding error so I want to get some more accurate values.

 

[Woody007]

That means the flow rate is much higher with the new pump than it is with the old pump.


So at full speed, flow rate estimate is around 62 GPM which is fairly low for that pump and would suggest fairly high head loss of around 84'. But even so, that is more than enough flow rate to purge the pump basket of air. So if there is still air in the pump basket at full speed, there is an air leak somewhere.

Could you post a picture of the filter gauge at both 3450 RPM and 3000 RPM? There is a bit of a disconnect between the two measurements and it could just be rounding error so I want to get some more accurate values.

If there's any rounding error, it's likely me. 3k rpm is 87% of 3450, right? The app shows flow rate or percent speed. No direct rpm that I've seen. I have it set to 3K for my filter reference. Today the filter is reading 22 psi at 3K and 27 at 100% rpm so my memory was incorrect on the full speed pressure. Is the pump capable of > 100% rpm to achieve a flow rate? I doubt it, but I may have be using flow rate when I looked and thought it was 30 psi.

 

[mas985]

If there's any rounding error, it's likely me. 3k rpm is 87% of 3450, right?

Yes it is but what are you setting in the pump controller, 87%? Mine only goes in 5% increments so that is why I ask.

The app shows flow rate or percent speed. No direct rpm that I've seen. I have it set to 3K for my filter reference. Today the filter is reading 22 psi at 3K and 27 at 100% rpm so my memory was incorrect on the full speed pressure.

So those two PSIs do match the predictions so that is all good. What does app say the flow rate is at each RPM?

Is the pump capable of > 100% rpm to achieve a flow rate?

Unfortunately, no. 100% is as high as it goes.

 

[Woody007]

So if there is still air in the pump basket at full speed, there is an air leak somewhere.

For what it's worth, when I use the booster pump the basket clears up and is full of water. I've watched closely and see no air at all coming in the suction side when the basket is full of water. Seems like if there were a leak I'd see air at that point.
It's like it gets air in the basket and it just keeps tumbling around at the top.

 

[Woody007]

Yes it is but what are you setting in the pump controller, 87%? Mine only goes in 5% increments so that is why I ask.

It actually does tenths. 86.9 is my current setting.


So those two PSIs do match the predictions so that is all good. What does app say the flow rate is at each RPM?
86.9% speed is showing estimate flow of 54 gpm and 100% rpm is 62 gpm.


Unfortunately, no. 100% is as high as it goes.

 

[mas985]

For what it's worth, when I use the booster pump the basket clears up and is full of water. I've watched closely and see no air at all coming in the suction side when the basket is full of water. Seems like if there were a leak I'd see air at that point.
It's like it gets air in the basket and it just keeps tumbling around at the top.

The booster pump will increase the flow rate through the main pump. Given that the amount of air you will see from a leak is usually dependent on the flow rate, one explanation is that the bubbles are just smaller in size so more difficult to see.

Another explanation is that given the higher flow rate, this will also increase the suction level in the pump basket which could make for a better seal in the pump basket.

To confirm, one test that you can do, is run the pump on full speed with the booster pump on and wait for all the air to "disappear". Then purge the air in the filter by opening the purge valve. Then let that run for some time and then see if any more air collects in the filter by opening the purge valve again and see if any air comes out.

Also, does the air level change in the pump basket at all between 3000 RPM and 3450 RPM? You may need to run for a few minutes to confirm as it takes some time to purge the air.

Another check, make sure the pump basket is free from debri as well as the impeller inlet at the bottom of the pump sump.