Variable speed or multiple single speed pumps

[Mike_Snoo]

Hi all,

my name is Mike and I am new to the forum. I have an in ground 20.000 gal pool with a 1.500 gal hot tub. I have a DE filter, a solar heater on the roof of my house and a currently not used/working gas heater.
My pool was originally built in the year 2000. As a saltwater pool. When I bought the house 2 years ago, I resurfaced the pool. I replaced the complete electrical control unit with a self made pool automation system. Which is integrated in my home automation system. The salt cell was not working and I switched back temporary to a chlorine based pool.

The pool was operated by a single speed pump for the filter and another pump for the jacuzzi bubble creation ( I don´t know the right word for that).

I recently upgraded to a Haywards Ecostar 3HP variable speed pump and have nothing than issued. First the drive went out and I replaced it with a regular Variable Frequency drive, than the motor had a short cut to ground. I found out that I would use the variable speed pump mostly on 2 settings. Low speed for general filtering, and a higher speed setting for all other demands.

The main reason why I need a slower speed pump is: I bought an AOP 25 UV Ozone Generator for sanitizing the pool which requires at least 10h of running pool pump per day.

I am also thinking of completely re pluming the pool pump area. It seems to me, that installer used as many 90degree elbows as possible.

Whit that being sad and seeing the Reported WEF (kgal/kWh) at the energy start website, I found out that lower HP pool pumps seems to be more efficient. WEF around 11, while lager pumps go down to 7.

I was think of instead of installing an expensive 3HP single speed pump, I could install 2 or 3 single speed pumps in the 1HP class. This has multiple advantages to me: I have redundancy, I save investment costs, get to a higher WEF.

I wanted to test the flow, power consumption on my current variable speed pump, in order to find out, when I get the maximum flow by minimal energy consumption. Unfortunately the pump failed before I even came to that. But what I read is that centrifugal pumps have only a high efficiency at the rpm they are built for. Means a variable speed pump, can only be a compromise.

What do you think about that idea? Did I missed something?

Looking forward to a nice discussion,

Mike

[Teapot]

Mike, I have a 12000 gallon pool which I run on filtration at around 70watts and that is 24hrs and 4 turnovers. Getting rid of knuckle bends is vital for efficient flow. You are of course correct that impellers have a sweet spot but also above water line hydraulics means even less efficiency as the impeller has to also be capable of priming whereas flooded flow, below the water line the impeller just needs to push.
Slower filtration is far better filtration.

[Mike_Snoo]

Hi Teapot,

you are absolutly right with the hydraulic below water level. Unfortunatly, I can´t change that.

What is your water flow with 70 watts? That seems like extremly low.

Is the 70 watts coming from the display of the Pool pump or did you measure it?

Here in the USA there is a lot scam going on with variable speed pumps. The average pool sales person can not bring anything more up than: a variable speed pump saves money.

Mike

[Teapot]

Hi Mike, its around 1800 US gallons per hour. Measurements taken from my multimeter. Flow was measured with ultrasonic flow meter.

[David00]

Mike,

You may find the latter part of this exchange I had with Teapot of interest if you are already using solar, and want to explore that further: viewtopic.php?f=49&t=14287. I believe Lorentz has distribution in the US.

It's just a option, I understand many people who have grid power wouldn't go down this route

Cheers,
David.

[Teapot]

David & Mike,
I did an install in Spain where mains power wasn't available using solar. I am not really a fan of the Lorentz pump as I have achieved better with less solar panels and with lower noise and higher flow rate which in turn allows me to wind things down on filtration.

Mike just to re-iterate, the flow rate I use gives my pool a 6 hour turnover and runs 24 hours so providing 4 turnovers, much better water quality and less cleaning. The down side of 24 hour running is having to empty skimmer baskets more frequently. I use about the same amount of electricity running 24 hours as most other pools burn in just 2 hours of running so it's really low cost running with better filtration.

[Mike_Snoo]

Hi,

I have already 2 Solar systems on the roof, one for the pool heater, one for engery production. I attached 3 files, one is the smart meter from Florida Power, one is the pool temperatures, where you can see that the variable speed pump putts a lot heat in the pool when it´s running all day ( 7:30 - 18:30 ), the last one is the Solar produced Energy. All files are from July 30th 2020 with the variable speed pump running.

I will follow up with another post in a few days with the single speed pump. Running from 10:45 until 14:45. It takes some time until my smart meter readings are available.

I don´t think the variable speed pump saved me any money, but it could be that it turned around the water more often than the single speed. I need to measure that and I also need to measure the real energy consumption of the pumps.

I got the spare parts for the variable speed pump and hopefully at the weekend, I am able to repair it.

Mike

[David00]

Hi Teapot,

My main motivation for using Lorentz was I wanted to keep my pool power system completely separate from house power, and didn't want the cost of a large battery array to power an inverter for the pump.

Out of interest, what was your configuration is Spain? I suspect at some point my Lorentz system will need replacing, and I'm interested in knowing about alternatives.

Thanks,
David.

[Teapot]

Hi David,
We did have to use an MPPT and inverter with battery bank for 24 hour filtration. That's where I learnt lead acid batteries are not very good so more batteries needed than LiFePO4.
Using a Blue Eco pump. Most important to the low energy setup and most variable speed is to get rid of as many flow restrictions as possible. My filter gauge pressure on filtration is 0.5PSI, the conventional pool setups with 10-14PSI is just system restrictions and friction and wasted energy.

[Mike_Snoo]

So, I measured the energy consumption of my 1.5hp single speed pump. Running daily from 10:45 until 14:45. I have 242V and 8.5A brings it to roughly 2000VA. I don't have an active power factor measurement device.

I also added some more pictures to compare the picture above from the variable speed pump to the single speed pump.

This are the single speed pump running from 10:45-14:45

[Mike_Snoo]

Hey Teapot,

I ordered a new measurement device which is supposed to be delivered Saturday. But yesterday I measured the energy consumption of the variable speed motor. The motor with no pump or whatever connected had roughly 240VA in idle, no matter of 600rpm or 3400rpm. You mention your pump has 70 Watts. That sounds extremely low. How did you measure the energy consumption of your pump?

[Teapot]

Hi Mike, the controller displays the power and current draw, however I checked these with my multimeter and there was a slight discrepancy of approximately 5 watts.
Yes it is very low, as said on another thread it was set to give 4 turnovers in 24 hours which is around 99% of the water being filtered according to Gage-Bidwells law of dilution. Any faster flow gives worse filtration and simply wastes electricity.

[Mike_Snoo]

Hmm, interesting. What kind of pool pump do you have?

I have the Hayward Ecostar variable speed pump sp3400vsp 2.7HP. The drive went out and I replaced it with a regular frequency drive. I also have a Pentair Whisperflow 1.5Hp.

The 5watts difference might come from the power factor. Unless you can measure that, you can't compare the Watts from the drive with the V*A = VA from the Multimeter.

I borrowed from the company I work for calibrated measurement devices. So I know that what I measure is real. The only think I can't measure right now is the power factor. I ordered this measuring device to really see how much power consumption is. https://www.ebay.com/itm/112553629684 It will arrive Saturday and I can follow up with more tests and information.

[Teapot]

Hi Mike,
It's not just about the pump, if that pump (Blue Eco) was put on a standard setup such as yours it simply would not perform. The pump is part of the overall setup I built to see just how low the energy usage could be allied, to how good the filtration can become. I have built systems for customers based on my design and they are also as amazing. The pump won't self prime, it's a flooded pump. The pipework was sized for minimal loss and flows into the pump, the pump lifts the water about 1 foot and the return pipework runs downhill. only radius bends are used and kept to a minimum, othe pipes are heat formed to fit curves. Slightly less glass filter media in the sand filter although that filters far better than any sand or other glas due to it's additional activation, (Dryden Aqua AFM glass). On one of my customers pools we cut through the pad slab to get the pump below the water line and no multiport valves. It may not be the issue with your DE but domestic sand filters do not backwash clean very well at all, leaving a fair amount of dirt behind so I fitted an air scour system to purge the dirt with air and water rather than waste a lot of valuable water.

[Mike_Snoo]

Ah, Ok, That make sense. I looked at the pumps, unfortunatley their website is not giving to much information. It is https://www.blue-eco.nl/en/ right?

I got my measuring device for the power factore. It is 0.93 means my pool with the 1.5hp pump is pulling around 1.8kW. The variable speed motor without load was between 134 and 175W (60 and 180hz).

I will install the flow meter over the weekend and see how much GPM I have. Than I start repluming.

I found it quite interesting. If I bypass my Solar roof heater and the water needs to make a 90 degree turn in a 3 way valve, I have 70W more energy consumption.