Pool Pump Performance Questions

[Nochain]

Replaced my single speed Whisperflow 1.5hp with a 1.5HP Calimar VS pump. Wanted a 3hp version but due to funding and availability I thought that the swap might be good enough.

Looking at the specifications I think what i am seeing makes sense but want more information about general pool pump operation.

I am getting about half the pressure in my cartridge filter from about 10psi to 5psi at maximum speed (3450rpm). Is this a problem (ie 5psi)?

The information I was able to obtain indicated about 40% hit on gpm flow rate from the new variable speed pump compared to the Whisperflow even though that was a 1.5 hp motor as well.

At 3450rpm with my new vs pump my pool vacuum work’s adequately and the skimmer as well. However at 1500rpm the pressure in the filter tank is 0! I do get a very small flow out of the filler exit ports and see flow into the skimmer albeit not much. Is this normal operation (ie 0 psi?) ?

It appears that my new pump is probably on the small for my pool (13k gal) but maybe I just don’t understand how variable speed pumps and their systems operate and what to expect?

Comments?

 

[Texas Splash]

No doubt your filter and outlet pressure will appear lower now that you have the ability to run a pump at ~1,500 rpm or so. When my pump is on low speed (1,750 rpm), my filter pressure gauge barely moves. However to compare spec-to-spec between the the Whisperflo and Calimar, let's ask @mas985 for some assistance to see if you are actually comparing apples to apples here.

 

[mas985]

I am getting about half the pressure in my cartridge filter from about 10psi to 5psi at maximum speed (3450rpm). Is this a problem (ie 5psi)?

Not a problem if the reason is lower flow rate. If the Calimar has a lower head curve than the Whisperflo, it will deliver less flow rate on the same plumbing. A 5 PSI filter pressure change is about a 25% reduction in flow rate.

The information I was able to obtain indicated about 40% hit on gpm flow rate from the new variable speed pump compared to the Whisperflow even though that was a 1.5 hp motor as well.

What information is this?

At 3450rpm with my new vs pump my pool vacuum work’s adequately and the skimmer as well. However at 1500rpm the pressure in the filter tank is 0! I do get a very small flow out of the filler exit ports and see flow into the skimmer albeit not much. Is this normal operation (ie 0 psi?) ?

Yes it is normal for low RPM. Flow rate is proportional to RPM so 1500 RPM will have a flow rate that is less than half that of 3450 RPM. The pressure will drop by over 70% but PSI gauges bottom out at around 3 PSI.

It appears that my new pump is probably on the small for my pool (13k gal) but maybe I just don’t understand how variable speed pumps and their systems operate and what to expect?

For general circulation, a smaller pump is not a problem. It only becomes an issue if you have high flow rate requirements such as a waterfall or spa jets.

 

[Nochain]

Thanks. The information I was referring to is the flow curves for each pump. The Calimar is a lower flow pump but from what I am hearing from you all seems to be normal given that this pump is just not as powerful as the Whisperflow I had. Given how the VS pumps operationally work in the system ie slower flow longer duration it seems that I am probably not that low off ideal. I think I’ll need to modify the program and use higher speeds on some of the lower settings…not a big deal.

 

[generessler]

Too late, I know. Anticipating this kind of uncertainty is why I added a flow meter before switching to a VSP. Not necessary, but nice for a number of reasons. nb: the 1.5hp Whisperflo - which I also had - is a beast. It was pushing 105 gpm through what I think is average 2" plumbing.