Moved from Hayward Super Pump to VSP - Issues at low RPM

[adamh007]

First time posting but really appreciative of this site and the helpful forums. I'm a new pool owner who bought a house with an older 20x40 33k vinyl pool in NJ. The pool wasn't opened for 10+ years and I brought it back to life using the guidance from this site. Plus I've saved hundreds in chemicals by avoiding the pool store for maintenance chemicals.

The pool had a 1HP Hayward Super Pump that died and I replaced it with a VSP (Century VGreen EVO Variable Speed Motor 1.65 HP 230/115v | EVC165). I didn't want to change the electrical connection so my options for a 115v motor were limited. I replaced all the pump gaskets and orings and applied silicone based lube. I've noticed that the pump works great at high RPM but when the RPM drops to ~1250RPM (or lower), there's no flow out of the returns at all and 0 PSI.

I don't like how I cannot customize the RPM on this model and have to pick a fixed schedule. Here's the owner's manual. At 1250 RPM, there's no flow out of the returns and basically the motor runs with lots of air in the pump basket. Any advice or guidance?

The pump is wired to a timer so I can schedule the pump to stop after 10 hours so it doesn't go to the lower RPM and just spin. I know the lower RPM is where the real electricity cost savings comes into play. The most recent schedule that I used that seemed to mostly work was 3450 RPM for 2 hours, 2850 RPM for 2 hours, 1850 RPM for 6 hours, and 1250 RPM RPM for 2 hours (doesn't create any flow in the returns).

 

[mknauss]

motor runs with lots of air in the pump basket.

Welcome to the forum.
That implies a suction side air leak. Or a very dirty filter. What does the pool water look like?

 

[adamh007]

Welcome to the forum.
That implies a suction side air leak. Or a very dirty filter. What does the pool water look like?

Pool water is clear. I haven't opened the sand filter yet.

 

[Jimrahbe]

Adam,

Why are you running anything faster than 1850 RPM?

If 1850 works, what do the faster speeds do for you???

You can only run at 1200, or so, if you do not have a heater. Heaters add restrictions to the water flow and (depending on the specific pump) means that you will have to run 1500 to 2000 to get good flow.

Thanks,

Jim R.

 

[Jimrahbe]

I haven't opened the sand filter yet.

Adam,

What does that mean?? Are you just by-pass the filter or what???

Thanks,

Jim R.

 

[mknauss]

@Jimrahbe
This EVO motor is not a real VS system. It is multispeed. And you have to use the schedules it has, you cannot change them.

 

[adamh007]

Adam,

Why are you running anything faster than 1850 RPM?

If 1850 works, what do the faster speeds do for you???

You can only run at 1200, or so, if you do not have a heater. Heaters add restrictions to the water flow and (depending on the specific pump) means that you will have to run 1500 to 2000 to get good flow.

Thanks,

Jim R.

On this particular model, I can't set the RPM. I have to follow a particular programmed schedule. I would love to set it for just the lowest working RPM. But I don't have control.

and when I said I didn't open the sand filter yet. I meant, I'm using it but I haven't physically opened the sand filter to inspect the insides.

 

[Jimrahbe]

you have to use the schedules it has, you cannot change them.

Marty,

So.. I read the manual... and that is the dumbest set of schedules I have ever seen..


Adam,

Sorry, I did not understand how your pump (motor) worked.

When was the last time you backwashed the filter?

Thanks,

Jim R.

 

[mknauss]

So.. I read the manual... and that is the dumbest set of schedules I have ever seen..

yeah. We need to start recommending NOT to get these motors.

 

[adamh007]

yeah. We need to start recommending NOT to get these motors.

Too late for me but it might help others. Very unfortunate. Although it was a super easy install, it seems like it's not a true Variable Speed and since I have less control = more headaches. I can backwash again soon but I need to open up the sand filter and replace some old orings and gaskets since the equipment hasn't been touched in many years.

 

[Hootz]

Unless there is a specific need to run at higher speeds, you could consider a schedule that runs a constant speed such as schedule 5 (set a). You get a 3 minute prime and then a constant speed for 24 hours at 1725 rpm. You can use the timer for less than 24 hour use. If during a schedule you need faster speed you can overide to 3450 rpm.

 

[hexabc]

With your pump and motor you will need 1725 rpm to get a flow sufficient to create a good skimming action. Compared to 3450 rpm of your old motor, that's a big saving, provided you can run the pump for let's say 12 hours, instead of 24. You can achieve it with schedule 5A by powering the pump from a timer, as @Hootz has suggested.

Remember that the power change applied to the pump shaft is proportional to the cube of RPM change. In your case you will reduce the speed twice, so the power will be reduced 8 times. Assuming the efficiency of the motor is 80%, the consumed electric power will be reduced roughly 6 times.

 

[adamh007]

Just an update. I bought some new o-rings for my sand filter and I was able to get flow out of my returns at lower RPM. I'm now running the pump at night at 1725 rpm with a timer. Appreciate all your advice!