Setting up a new Pentair WhisperFlo VST variable speed pump

[ba67]

A licensed pool professional just installed a Pentair WhisperFlo VST pump and didn't show us how to use it afterwards. The owner's manual doesn't give any advice regarding programming speeds or schedules. If anyone on here has this pump or has a similar Pentair variable speed pump, I have a few questions that I hope someone on here would answer for me:

If we want to keep the pump off for 10 hours at night to keep the skimmer from filling up with leaves during the night, how many RPMs should we operate the pump during the day?

Should we increase the speed at 7 PM when we normally add liquid chlorine? If so, how many RPMs should we increase the speed to, and how long should the pump operate at that speed before the pump turns off for the evening?

Is it normal for your sand filter to register a higher than normal filter pressure after getting a variable speed pump installed? Clean pressure is at 32 now, which is higher than normal. When we turn the pump off, it only goes down to 22, instead of 0. Is this a sign that the gauge is broken or is this normal? If this is a sign of a broken gauge, do I need to replace it before starting a SLAM tomorrow or can I just backwash when it goes up by 20%?

How many RPMs should I set the pump to during a SLAM? Should I increase the speed for an hour or two after adding chlorine each time or can it run at the same speed for 24 hours a day until it clears up?

When vacuumming the pool with a manual vacuum during the SLAM or afterwards, do we need to increase the RPMs? There is a Quick Clean button that you can press when you want to temporarily increase or decrease the speeds during cleaning.

 

[mas985]

If we want to keep the pump off for 10 hours at night to keep the skimmer from filling up with leaves during the night, how many RPMs should we operate the pump during the day?

To save the most amount of energy, you will want to run the pump on the lowest RPM possible but there is no need to go much below about 1000 RPM as energy use flattens in that range. With manual LC dosing, the only other factor is skimming and you want to make sure water travels over the top of the weir door rather than around the sides.

Should we increase the speed at 7 PM when we normally add liquid chlorine? If so, how many RPMs should we increase the speed to, and how long should the pump operate at that speed before the pump turns off for the evening?

No need to do that as long as the run time is at least 60 minutes after dosing.

Is it normal for your sand filter to register a higher than normal filter pressure after getting a variable speed pump installed? Clean pressure is at 32 now, which is higher than normal. When we turn the pump off, it only goes down to 22, instead of 0. Is this a sign that the gauge is broken or is this normal? If this is a sign of a broken gauge, do I need to replace it before starting a SLAM tomorrow or can I just backwash when it goes up by 20%?

Pressure is dependent on the make/model of pump so replacing a pump will likely have a different pressure than the one before. So assuming that the speed of the pump is at full speed, 3450 RPM, then yes, the pressure could be much higher than your old pump if your old pump was smaller than the current pump.

How many RPMs should I set the pump to during a SLAM? Should I increase the speed for an hour or two after adding chlorine each time or can it run at the same speed for 24 hours a day until it clears up?

As with dosing it is unnecessary to change RPMs for a SLAM. The only reason would be if you want clear the surface of debris quicker.

When vacuumming the pool with a manual vacuum during the SLAM or afterwards, do we need to increase the RPMs? There is a Quick Clean button that you can press when you want to temporarily increase or decrease the speeds during cleaning.

Vacuuming could possibly require higher RPM depending on how the vacuum is connected and the other valve settings. Experimentation is warranted to determine the minimum RPM necessary for your vacuum to work properly.

Every pool is different and will require different RPM for various functions so you will need to experiment some to find the lowest possible speed for each function.

 

[ba67]

Pressure is dependent on the make/model of pump so replacing a pump will likely have a different pressure than the one before. So assuming that the speed of the pump is at full speed, 3450 RPM, then yes, the pressure could be much higher than your old pump if your old pump was smaller than the current pump.

Should the pressure go to zero when the pump is turned off like it did before with my old single speed 1 HP pump? I just want to make sure that this gauge is accurately working so I will know when it is time to backwash during a SLAM. My new pump is larger than the old one so its good to know that the pressure could potentially be higher.

 

[mas985]

Should the pressure go to zero when the pump is turned off like it did before with my old single speed 1 HP pump?

Yes

 

[Jimrahbe]

Ba,

Filter pressure is directly related to your pump speed. The faster you run, the higher the filter pressure.

I run my pump at about 1200 RPM, most of the time, and my filter pressure is about 1 lb.

32 PSI, seems awful high to me, unless your were running full speed.

Thanks,

Jim R.

 

[ba67]

Yes

Ba,

Filter pressure is directly related to your pump speed. The faster you run, the higher the filter pressure.

I run my pump at about 1200 RPM, most of the time, and my filter pressure is about 1 lb.

32 PSI, seems awful high to me, unless your were running full speed.

Thanks,

Jim R.

The pump speed is set at 2400 now and the filter pressure is 32 PSI. Is that full speed? When I turn the pump off, the filter pressure only goes down to 22. If the pressure should be going down to 0 when my variable speed pump is off, does this mean that I need to replace the pressure gauge? Can I go ahead and start the SLAM without replacing the gauge and backwash when it goes up 25% (or gets to 40 PSI)? I don't live near a pool store so I don't want to go out to get a new gauge until Monday unless I have to. I also need to know what RPMs to set my pump to during the SLAM. Its currently set to run for 24 hours at 2400 by my pool guy but I wasn't sure if this was a good speed to keep it at or not.

 

[mas985]

The pump speed is set at 2400 now and the filter pressure is 32 PSI. Is that full speed? When I turn the pump off, the filter pressure only goes down to 22. If the pressure should be going down to 0 when my variable speed pump is off, does this mean that I need to replace the pressure gauge?

Yes

Can I go ahead and start the SLAM without replacing the gauge and backwash when it goes up 25% (or gets to 40 PSI)?

It is going to make it harder but instead of gauge, you can use your hand to feel the flow strength from a return to determine when the filter is getting clogged.

I don't live near a pool store so I don't want to go out to get a new gauge until Monday unless I have to. I also need to know what RPMs to set my pump to during the SLAM. Its currently set to run for 24 hours at 2400 by my pool guy but I wasn't sure if this was a good speed to keep it at or not.

You probably could set it lower it you wanted to. As long as the water is moving, it won't matter that much if the RPM is high or low.

 

[Jimrahbe]

The pump speed is set at 2400 now and the filter pressure is 32 PSI. Is that full speed?

At full speed, the pump would run at 3450 RPM..

Sounds like your Filter gauge is bad and needs to be replaced.

Since you have a heater, you will most likely have to run between 1500 and 1800 RPM.

Thanks,

Jim R.