Varible speed pump began running too fast

[tonto]

I have had a variable speed pump for three years and have been pleased with it. It has been running at about 310 watts for 12 hours daily with clean filters. When the watts go up to 410 I backwash the system and start over again at 310 watts. The system has worked well until recently. A month ago I noticed my pump was running at 515 watts so I backwashed the system. Then, even with clean filters it continued to run at 515 watts. I backwashed again to no improvement. I inspected the water inlets to the pump and cleaned the pump bowl and found everything in order. What could be the problem? I switched to the variable speed pump to save electricity, but at 515 watts I am no better off than with my older fixed speed pump.
I have a Pentair Intellliflow VF pump with Intellitouch control system. My filter is a 48 square foot Haywood DE, and the pool is 10,000 gallons.
Any constructive advice would be greatly appreciated.
Thank you.

 

[Jimrahbe]

Hi Tonto,

At one point you say you have the Variable Flow pump and at another point you say you have the Variable Speed pump.. which is it?

Not sure what pump you had before, but a single speed 1 HP motor draws about 1500 watts on a good day, so you are not as bad off as it could be.

Where are you reading the wattage? Can you also see the actual pump speed?

Jim R.

 

[thepoolman]

Have you pulled your filter apart and cleaned your grids lately? There is residual DE that builds up that is not removed when backwashing. This could cause what you're seeing.

 

[pooldv]

Variable flow pumps are set to maintain a specific gallon per minute flow rate. It will use as much electricity and speed as required to maintain that GPM, up to the max speed of the pump. There are only a few things that come to mind that could cause flow restrictions requiring the increased pump speed to maintain the flow. Clogged filter, dirty skimmer or pump basket, a debris blockage in the suction side plumbing, a valve being closed more than it was before, changing eyeballs on the pool returns.

Conversely, a variable speed pump will maintain a certain RPM setting at all times and the GPM flow will be reduced as the filter gets dirty or if other water flow restrictions develop. Which is why my SWG works fine at 900 rpm with a clean filter but the pump must be run at 1100 rpm with a dirty filter to avoid low flow errors.