Variable speed pump

PULIO · May 29, 2016

We have an indoor pool. We used to run the pump about 8 hours a day, usually at night when electric rates are lower. However, we had some problems with our HVAC dehumidification system which requires that we run the pump 24/7 for constant circulation. I was concerned about our electric bills so we recently replaced the pump with a Jandy Pro Series Plus HP PHPF.50 at the suggestion of our pool mechanic. He said we would run 24/7 at about the same cost of the previous pump running 8 hours a day.
I wanted to replace with variable speed pump but our pool guy dissuaded me because we have a solar heating system on the roof and he said a variable speed pump would not be able to pump the water through the roof panels (ironically, my solar installer recommended the variable speed pump).
Anyway, our electric bill is still pretty high - maybe not as high as it would have been with the old pump but I'm wondering if a variable speed pump would still make sense. From what I have read they are much more economical. Anybody know anything about this??
Thanks

Divin Dave · May 29, 2016

Hi Pulio,
A variably certainly will pump water to the Solar Panels.

Depending on how large the pump is, and how many head ft you need to pump water to the solar panels, will largely determine how much more econimcal it will be on the electric bill. When it comes to VS pumps, running larger HP pumps to attain x GPM of flow is actually more cost efficient than running a smaller VS pump. The reason, is because you can run the larger pump at lower RPM than you can the smaller pump.

RPM = Watts, and thats what you pay for on the light bill.

pooldv · May 30, 2016

I have a Pentair Intelliflo, 011018. It is a 3hp pump at max speed, 3450 rpm. I run my pump at 1100 rpm for skimming, filtering and making chlorine with my SWG. It uses 150 watts at 1100 rpm. It also runs in solar standby mode waiting for the Pentair Solartouch to detect solar heat is available. When heat is available the Solartouch opens the solar valve and ramps the pump speed to 1950 rpm, it uses 550 watts at 1950 rpm.

At 10.25c/kWh I can run the pump 24x7 for 12 bucks a month.

Statesman · May 31, 2016

Re: Variable speed pump - what speed?

I'm not sure if I need a new thread, but a new pool guy, same company, changed the speeds and times of my Pentair variable speed pump last week from last summer's settings, from 1800 to 3000 rpm from 2 pm - 6 pm daily, which is relatively noisy when we're outside. He scheduled low speed from 8 am - 2 pm at 1800 rpm daily. Last summer they told me to run only a few hours per day and high speed maybe 2 hours, later in the evening so we don't hear it. Considering my new SWG 16x36 pool, 7' deep with sporadic use (sometimes 15 kids, then we go days without using it). The pool looks beautiful and there are no trees around for debris. Is this necessary? I'm afraid to see my electric bill this month!

pooldv said:
I have a Pentair Intelliflo, 011018. It is a 3hp pump at max speed, 3450 rpm. I run my pump at 1100 rpm for skimming, filtering and making chlorine with my SWG. It uses 150 watts at 1100 rpm. It also runs in solar standby mode waiting for the Pentair Solartouch to detect solar heat is available. When heat is available the Solartouch opens the solar valve and ramps the pump speed to 1950 rpm, it uses 550 watts at 1950 rpm.

At 10.25c/kWh I can run the pump 24x7 for 12 bucks a month.

pooldv · May 31, 2016

No, not necessary at all. Keep lowering the RPM until you get a low flow error on your SWG. For mine it was 900 rpm, which is why I run at 1100 rpm. I never get a low flow error at 1100 rpm, I would get occasional low flow errors at 1000 rpm.

Once you determine what makes the SWG happy run it at that speed for 6 or 8 hours a day and see how your pool looks. If it is good then you can either shorten the time or leave it alone because it is cheap enough. If it is dirty then you can extend the time to 8 or 10 hours or set a second timer for a higher speed for an hour or two, maybe 1800 rpm to start.

One more point, pay attention to the watts used, some folks notice that their pump uses the same watts at 1100 or 1200 rpm as it does at 1200 or 1300 so you should set to the higher RPM that still consumes the same watts. Got that?

RobbieH · May 31, 2016

FWIW, in case someone comes here looking at pumps for solar panels, the VS pumps will work with solar panels, the VF will not. That is what Pentair told me anyway - so I can't put up solar panels with my current pump.

Now, back to your question. If you are not needing to power anything (suction/pressure side pool cleaner, etc.) then you can probably get by on running on slow speed all the time. I put together a spreadsheet and found that if I run somewhere between 1700 and 1800 RPM, that is the really efficient range in my pump to turn over the water somewhere between 90% and 110% per day running 24 hours, for the lowest electricity use. You may very well be in the same boat. In fact, my water is so clear right now, I'm considering lowering the RPM even more, because there's some more savings to be had if I go down to 1400 RPM.

Note I have a really large pool, so you might be able to lower even further than me (if SWG is happy) or be able to run less than 24 hours. In my case, so far running very low for 24 hours is more efficient power-usage wise than trying to run partial days.

Poolray · May 31, 2016

I run the VS at 850 RPM from 9AM to 9PM. Solar kicks in when needed, and raises the motor speed to 2600 during those times (It could go lower but then air gets sucked thru the panels which I haven't figured out yet). VS is the way to go because once its tuned right, it will not only save electricity, but should theoretically last longer because its being stressed less. You may never even need the full speed setting.