Quiet Pump

[bradj]

I'm finishing up a pool build and my water features have a 1.5HP pentair Whisperflo pump Model #011773. The pool/spa pump is a pentailr VS 3PH model# 011018. The water feature pump is way too loud and needs to be changed out. The 3HP Pool pump at full speed setting is probably half the dB of the "Whisperflo" pump.

I'm going to see if the PB will swap it out with a quieter pump, if not any ideas of quiet single speed pumps? I don't mind buying another VS pump if that is the only route to get the sound level needed but would rather save the money with a lower HP single speed since the pumps only requirement is running (3) 24" water sheers.

Is it possible to just purchase the motor/VFD assembly for the same VS pump I currently have and mount onto the 1.5HP pump housing(correct term?)

 

[RedBluePool]

You would need the motor, drive, and the impeller to get that working

 

[azpoolpros]

Is is possible to swap the single speed for variable speed yes. wether or not it will help I dont know, sounds like the pump is staining to move the water around, could be a total dynamic head issue. ive had it where the pressure side just needed to be closed off a little and the system would quite down.

 

[bradj]

Is is possible to swap the single speed for variable speed yes. wether or not it will help I dont know, sounds like the pump is staining to move the water around, could be a total dynamic head issue. ive had it where the pressure side just needed to be closed off a little and the system would quite down.

I have regulating valves on each sheer, I'll play around with closing them off some tomorrow.

 

[JamesW]

The WhisperFlo is a high head pump, which means that it is designed to push water against a lot of resistance. Most water features have low resistance. In most cases, a WhisperFlo is a very bad choice for a water feature. Pumps all have a head curve. Within the curve is a designated best efficiency range.

The pump should always be running in the best efficiency range. Outside of the range, they can be very noisy. In some cases, the noise is caused by cavitation. Almost definitely, the Whisperflo is way to far to the right on its head curve.

A pump designed for low head would probably be a much better choice. It would be much quieter and it would use much less electricity. There are dedicated water feature and waterfall pumps. To get the correct pump, you have to know the specific requirements of the water feature.

Can you describe the water feature? Make and model. Height above water?
Do you want a solid sheet down to the pool surface?
What size pipes are the suction and pressure pipes?
How far is the pump from the pool?

 

[wjr75]

We replaced our main pool pump last year with a Whisperflo 1.5 hp and you can barely hear it a few feet away. I wonder if some back pressure is causing the increase of noise.

 

[JamesW]

It's not back pressure causing the noise. It's actually lack of back pressure causing the problem.

If there's less head loss on the pressure side, there's an increase of head loss on the suction side. If the head loss gets to about 32 feet on the suction side, the water can boil and convert into steam and create voids in the water (cavities, hence the name cavitation). As the steam goes from low pressure on the suction side to high pressure on the pressure side, it collapses creating a loud noise. This usually happens as bubbles, which make a sound like rocks or gravel traveling through the system

Adding resistance to the pressure side can quiet things down in cases of cavitation because it reduces the suction and can keep the water from cavitating. However, the best solution is to get a pump whose head curve crosses the system curve at the correct operating point and is within the designated best efficiency range.

Do you want a single effect from the sheers or do you want the ability to control the flow?

A medium head variable speed pump can be a good choice. You could also skip the extra pump and just add valves to send return water to the sheers. If you have automation, you can use valve actuators to run on a schedule.

 

[bradj]

Correct.. I choked the regulating valves down to the minimum flow to still keep a sheet of water out of each sheer and the pump is now extremely quiet!

The sheers are a one trick pony, so with their current valve positions and dB levels I am good to go.

It's not back pressure causing the noise. It's actually lack of back pressure causing the problem.

If there's less head loss on the pressure side, there's an increase of head loss on the suction side. If the head loss gets to about 32 feet on the suction side, the water can boil and convert into steam and create voids in the water (cavities, hence the name cavitation). As the steam goes from low pressure on the suction side to high pressure on the pressure side, it collapses creating a loud noise. This usually happens as bubbles, which make a sound like rocks or gravel traveling through the system

Adding resistance to the pressure side can quiet things down in cases of cavitation because it reduces the suction and can keep the water from cavitating. However, the best solution is to get a pump whose head curve crosses the system curve at the correct operating point and is within the designated best efficiency range.

Do you want a single effect from the sheers or do you want the ability to control the flow?

A medium head variable speed pump can be a good choice. You could also skip the extra pump and just add valves to send return water to the sheers. If you have automation, you can use valve actuators to run on a schedule.