Time for a new pump: Variable Speed vs. Variable Flow

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R

Red

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Sep 11, 2010
85
Orange County, CA
My pump motor started making a horrible noise last Friday afternoon. It turns out the bearings are shot on my pump motor and it's time to do something about it (fortunately, it doesn't bother my neighbor as much as it bothers me). A pool person could put on a new 2-speed motor or completely replace the pump with a variable speed pump. He originally recommended going with a variable speed, but after thinking about it, said due to my minimal setup, a variable speed pump might take longer to reach payoff than it would for some of his other customers. I think he's just trying to be honest and give me some options and different price points.

Anyway, I'm researching Pentair pumps and there are way too many to choose from. I also see there are variable flow pumps in addition to variable speed. I think I'm just looking at Pentair pumps. I've seen a lot of good things written about them and have had some issues with Hayward stuff.

So, here's what I'm looking at:
  • 011055 IntelliFlo 2 VST or 011018 IntelliFlo Variable Speed (I finally found the difference is whether or not I want the new, rotating panel; otherwise, I believe they are the same variable speed pump)
  • 011012 IntelliFlo VF (variable flow only)
  • 011056 IntelliFlo VSF (variable speed and variable flow)

What would help me decide to go with variable speed vs. variable flow vs. both?

All my plumbing is 2" PVC, unless otherwise noted.
I have no spa, but I do have some water features:
  • 4 deck jets (run to the pump and individually controllable via manual valves...probably 3/4" PVC)
  • A slide (I think this is 1" PVC...also run to the pump)
  • A lion head fountain. This is 1/2" plumbed in with the 2" return line loop that goes around the pool: not the greatest way to do it, but I added it near the end when the pool remodeler realized he needed to correct some things so that his correction would look better [omitting longer story]

Anyway, my guess is that variable flow would be potentially useful for making sure the water features work. I don't really have a problem with the 2-speed pump now. I put it on high and direct most of the output to the water features and they work.

What I've seen is that the lion head spout rarely works when the the pump is on low speed or if it's on high speed and I've diverted much of the return to the water features. If my filter has just been cleaned or backwashed, it will work on low speed for several days until the filter pressure starts increasing. Or if I close some of the returns, it will work on low speed. Otherwise, it just doesn't work.

I guess if I got a variable flow pump, I could find the right flow to make it work, and that might be an advantage. However, it's a also a more expensive pump. I suppose I could also find the right RPMs to make things work until my filter pressure builds up. I guess a variable flow pump would also help me calculate how much water is moving, as I'm setting GPM instead of RPM.

I'm not sure on the advantage of the VS/VF combo pump?

Are these the main considerations in deciding between variable speed and variable flow? Are there other things I should consider? I think the IntelliFlo VS2 is the only unit with a wall-mountable controller, which might be helpful and could be a motivation for that unit unless there are compelling reasons for variable flow. I've been browsing a lot of discussion about plumbing and pumps on the boards tonight, but I didn't see VS/VF discussions.

Thanks for any words of advice.
 
The variable speed pumps give you the ability to adjust the flow of the pump by dialing in the RPM of the motor.

With the variable flow pump you adust the GPM of the pump. The main difference though is the VF pump will automatically increase the pump speed to maintain the flow you have set to compensate for a dirty filter.

The thinking behind this has to do with old water filtration theory where the entire volume of the pool had to get run through the filter everyday (turnover). This has been proven to not be necessary so no need to waste the electricity to needlessly run the pump.

Taking that in to account, there is really no reason to consider the VF pump since you would be paying for features that are not needed and unnecessarily complicate things. The standard VS pump is capable of doing everything you need.

I see no reason why a 2 speed pump wouldn't work for your situation and it will probably be the most cost effective replacement, however check with your city and your power company to see what rebates they offer for pool pumps and it may be enough to offset the added expense of the VS pump.
 
Brian has you covered, but I noticed that you said your filter pressure increases after a few days. I believe you have an issue with your water as your filter shouldn't be increasing in pressure after a few days. I can go a year without my filter increasing in pressure and your filter is sized right for your pool size so I believe it should be able to go months without any increase in pressure.

Most often the reason for filters to increase in pressure for SWG owners is nascent algae. The SWG makes enough chlorine to kill off enough of the algae before it blooms but the filter is working by trapping the dead algae and thus the increase in pressure.
 
Red,

You left out the IntelliFlo 011018... See this Pentair IntelliFlo Variable Speed Pump 011018 | Pentair 011018

It is Last Year's model, but still a great pump.

The only negative is that the panel does not rotate. If using an automation system that does not matter, but if running manually it can be a PIA because the panel faces away from you if standing at the pump basket. If there is plenty of room a the equipment pad, that would not be a problem... but if your pad is tight, all the pumps that won't allow you to rotate the control panel, will make you stand on your head to operate them.

Thanks for posting,

Jim R.
 
Thank you for your thoughts. It looks like I'm down to either replacing the 2-speed pump motor or going with the variable speed. I also appreciate the thought that the 2-speed will likely be sufficient. I'll have to check on rebates. The pool repair person said since I got a rebate when I put in the 2-speed pump many years ago that the power company probably won't do one again to go to variable speed, but I'll check.

I'm not sure after how many days my filter pressure increases; it might even be a few weeks. Maybe I need to start logging that one on my spreadsheet. I don't think it increases a lot, but it's enough to keep the lion head from working on low. I've wondered how much the increase comes from debris (especially from winds), but you don't live too far away from me and have a different experience (I have to backwash a couple of times a year besides a cleaning). I haven't heard of nascent algae problems, but maybe that's what's going on. It looks like I need to search for threads on that and/or ask a new question in one of the chemistry forums. Thanks for suggesting it.
 
If you are a DIY'er, bearing replacement is not difficult. Alternative is to take to a motor rebuild shop. Both of these will be much less expensive than a new motor/pump. However, the vs pumps are nice!
 
peirek said:
If you are a DIY'er, bearing replacement is not difficult. Alternative is to take to a motor rebuild shop. Both of these will be much less expensive than a new motor/pump. However, the vs pumps are nice!
Click to expand...

I appreciate the idea and it's good to know for the future. It might be a fun project to figure out sometime. Right now I have so many unfinished DIY projects around the house that I ended up paying a pool repair person to come and get it done.
 
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