Replace Single Speed Pump to Save Energy?

[starman314]

Hi,

I'm trying to wrap my head around what I should do with my pool pump configuration on would appreciate any input. Here are the details:

50K gallon pool w/ integrated spa in Northern VA
Polaris 280 pool cleaner
Hydramatic pool cover that we keep closed whenever the pool is not in use
Autopilot SWG
Pool will be open from April through October

Current pumps:
Pentair 011018 IntelliFlo 3HP (we set this at 2100RPM to run the waterfall/stream feature when people are in the pool, that is currently its only use)
Pentair WFE-6 Whisperflo 1.5HP (this is currently our primary pool filter pump, it is one speed and is set to run from 5am-11pm every day)

We have energy monitoring on all circuits in our house. The pool house subpanel is currently using about 41kWh per day of electricity, which is a substantial portion of our total electric usage. I believe almost all of this usage is driven by the filter pump. Our electric cost is $0.12/kWh.

This is a brand new pool, so all of the equipment is at the beginning of its service life.

What is the best / most cost effective way to improve the energy efficiency of this setup? Some options I was considering were swapping out the motor on the WFE-6 for a two speed or swapping the InteliFlo in as the primary pool pump and trying to find a single speed pump that will generate the right flow rate for the stream / waterfall feature to replace it.

I would appreciate any input.

 

[mas985]

I would swap the two motors with impellers and diffusers. The WFE-6 should run the water feature just fine. Do you need a variable setting for that? What was the Intelliflo RPM when you ran that feature?

 

[starman314]

I would swap the two motors with impellers and diffusers. The WFE-6 should run the water feature just fine. Do you need a variable setting for that? What was the Intelliflo RPM when you ran that feature?

The Intelliflo is at 2100RPM when we run the water feature. We don't need variable speed for the water feature, but we do need something that will provide approximately the same flow rate, so that the water feature doesn't flow too hard or too soft. How can I figure out what single speed pump would match the flow rate of 2100RPM on the Intelliflo?

 

[mas985]

The Intelliflo at 2100 RPM will produce about 61 GPM on plumbing curve-c. The WFE-6 will produce about 88 GPM on the same plumbing. If you want to see what the WFE-6 would look like on the waterfall, change the Intelliflo RPM to 3000 RPM.

However, if you want to produce exactly the same flow rate as the Intelliflo @ 2100 RPM, you just need to replace the WFE-6 impeller with a 1/2 HP impeller. You can keep the same motor.

 

[JoyfulNoise]

Listen to Mark, he's the expert.

But I have to say, WOW, that's a totally backwards hydraulic design?!?! The IntelliFlow should be used on the filter/SWG so that you can maximize efficiency - use just enough RPM's to generate chlorine and, when not generating chlorine, use a really low and energy efficient speed for filtration. If you have it paired with an EasyTouch panel, then there's ways to program the SWG operation (pump speed and runtimes) separately from just a simple skimmer or pool cleaner cycle.

I went on-and-on about this last winter, but PB's always have this tendency to use high-head pool pumps on low head water water features (my waterfall is configured with an oversized 3HP WhisperFlow pump. It's a total waste of energy when the waterfall runs). It sounds like your water feature simply needs lots of water volume and not much pressure. If that is case, the PB should have used a Pentair waterfall pump which is a lot more energy efficient than a pool pump. Waterfall pumps are designed to move lots of water volume at lower pressure.

Well, you've got what you've got and Mark's advice is always spot-on so definitely consider what he says to do.

Good luck,

Matt

 

[dfahrion]

With a pool that is covered all the time, why do you have such a high run time on your filter pump? You could cut costs by over 75% just by reducing that from 5am-11pm (18 hours) to the recommended minimum of 4 hours. This year I've been running only 2 hours as 4 1/2 hour runs throughout the day if it isn't open and haven't found any problems with that, but I would recommend trying a reduction to 4 hours first. Assuming your 18 hour run time is based on a timer/controller that should be a few minutes of adjustments to get that 75% savings. Then you can decide if additional savings from switching around pumps/speeds is worth it or not.

 

[starman314]

Wow, you guys are awesome. Thanks for all of the suggestions. I really like Mark's idea of swapping the two motors, impellers, and diffusers and switching to a 1/2 HP impeller for the WFE-6. Is there a good tutorial somewhere that would help me understand how to do that?

I'm not really sure what the pool builders were thinking when they put together the pump configuration. The water feature is a stream that starts uphill and then flows back downhill into a waterfall. I'm guessing they just weren't sure exactly what pump speed would be require to get it working well, so they put a variable speed pump in there so we could tweak it. Now that we know the exact flow rate we need, we don't really need a variable speed pump there any more.

 

[starman314]

Spent some more time researching this. It looks like if I want to swap the two motors with impeller and diffusers, the steps are:

1. Unbolt the motor assembly
2. Disconnect the bonding wire
3. Disconnect the electrical

Reverse the process to reinstall.

Is that right or are there additional things I need to do?

 

[mas985]

You may not need to disconnect the electrical if you are just swapping the motors. They both still need to be powered, correct? Just make sure the breakers are off. If they are connected to a controller or timer, you can swap the leads there instead of at the pump.

 

[starman314]

Ok, I did it. Per Mark's suggestion, I made the Intelliflo the filter pump and the Whisperflo with a 1/2 hp impeller the waterfall pump. Everything appears to be working properly and I am able to control the Intelliflo through our Jandy Aqualink RS.

Now for the next question, what speeds and run times should I use for the Intelliflo? My previous program for the 1.5hp Whisperflo (WFE-6) had the filter pump running from 6am-6pm. Cleaning with Polaris 280 with booster pump from 6am-9am and spa mode from 1pm-2pm (the pool has an integrated spa). I think that gave us a little over one turnover per day. Our pool service set up that program, so I have no idea whether it is optimal / necessary.

I'm assuming I want to run at lower speed for longer and then increase the speed for cleaning + spa mode? The Jandy Aqualink defaults are 1750rpm for the pool filter and 2750rpm for cleaning and spa.

I have a Pentair FNSP 60 DE filter if that makes any difference.

I assume if I extend the filter pump runtime I will need to change the Autopilot SWCG settings?

 

[pooldv]

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I run my pump at 1100 rpm to skim, filter and make chlorine with the SWG. If you need more skimming then turn it up a bit to 1200 or 1400. 6 to 8 hours should be plenty. About an hour for the cleaner and spa should be enough, I'd try 2000rpm for that to start and see how it goes.