Question on Energy Efficient Pump Driving Caretaker In-Ground Cleaning System

[djcjdad]

Hello to all,

I live in Phoenix and have been trying to decide wether or not a variable speed pool pump is for me. I have read and watched all of the comparisons to regular induction style motors and the data is pretty impressive as far as energy use. My question is this...I current have a 1.5 year old Hayward 2.0THP RS pump filtering a 12,000 gallon pool with a Caretaker in-ground cleaning system. I know that the Pentair Intelliflo VS pump and the Hayward Ecostar pumps are multispeed, But I wonder how low/slow I can actually run either one of those pumps in my current system with the pop-up heads. I visited Caretakers website and they claim you need 15 PSI to drive 2 heads and then another 1 PSI for every extra head per station. I have 5 stations (16 heads total) with the largest station (6 heads) servicing the pool steps. According to caretaker I need a total of 19 PSI to clean the steps.

So back to the original question...would I have to run either one of those pumps close to top speed to clean those steps? How much time is really needed to run the cleaning system as opposed to just pool filtration which could run those pumps on a much lower speed? The Ecostar has a 24hr programmable timer able to run the pump at different speeds at different times.

My current hayward 2.0THP pump is a hog when it comes to power! I checked my daily APS (electric company) smart meter and It showed the pump alone demading about 2.2KW per Hour to run at 3450RPMs. These new pump claim they can run as low as 750RPM and only demand about 250 watts per hour. I would really like to save some money on my electricity bill.

Any help would be greatly appreciated.

Jeff

[PoolDoc]

Jeff,

Jeff, you've got a problem: "Energy-efficient" and "in-floor pool cleaning systems" are not phrases that go together, unless the sentence also includes the word, "not".

When you have to deliver 19+ psi AT THE PIPE END, instead a normal 3 - 4 psi . . . your pump HP requirements, and your electrical bill are going to be high!

There's really no way to be efficient AND use your Caretaker system. Their mode of operation is intrinsically 'expensive' in terms of energy. Having a VFD motor won't change that.

I don't recognize a Hayward "2.0THP RS" pump, but the VFD pumps from Hayward, PentairPool and others are not all that efficient on their wet end. They are not even especially efficient on their electrical (motor) end when compared to a PROPERLY sized and selected standard 2-speed pool pump. What they are, is genuinely multi-speed, which allows pool builders (and pool designers) who don't know how to calculate pool hydraulics, to put in a 1-size-fits-all pump, and then adjust it to the pool. And, a VFD pump WILL usually be more efficient than a BADLY sized and selected 2-speed pump.

No pool pump, running on low speed, whether it's a VFD or just a 2 speed, is going to deliver 20psi at the Caretaker heads!

I'm going to ask Mark, a regular contributor here who has very strong hydraulic knowledge, to take a look at this, but I think what I've told you is correct.

[mas985]

I agree with Doc. An in-floor system is the antithesis of energy efficiency. Energy use of any pump is primarly driven by flow rate and pressure (i.e. hydraulic power). So if you want the same performance out of the your in-floor system, the flow rate will need to be nearly the same to achieve the same pressure at each popup head and the hydraulic power will need to be the same no matter what pump is used.

As for efficiency of the pump, it can be broken down into two parts, the wet end pump efficiency and the motor efficiency.

Most variable speed pumps use the same wet end as the largest single speed in a pump line. For example, the Intelliflo uses the same wet end as the Whisperflo WFE12 and the EcoStar is the same as the Tristar 3220EE wet ends. So the variable speed wet end performance should be no different than their single speed counter parts that use the same impeller. But pump efficiency is also dependent on the impeller size, diffusor clearances and other factors. So in general, smaller pumps tend to have lower pump power efficiency but higher gallons/watt-hr efficiency. While the flow rate decreases for smaller pumps, the power use decreases much faster.

Motor efficiency is a different story. A VS pump, primarily those that use permant magnet motors such as the Intelliflo and EcoStar, have very effiicient motors and so their efficiency tends to be a little better than a single speed pump at the same flow rate (~5%-20%). But the increase in motor efficiency can be offset by a less efficient wet end design.

For example comparing your pump to the Intelliflo at the same flow rate using the CEC plumbing Curve-A:

RS2002: 67 GPM @ 2040 watts - 2 gallons/watt-hr

Intelliflo: 67 GPM @ 2067 watts (3300 RPM) - 2 gallons/watt-hr

EcoStar: 67 GPM @ 1771 watts (3300 RPM) - 2.3 gallons/watt-hr

The EcoStar actually does better than the Intelliflo which is probably due to a better wet end & VFD design.

How much you save and when the pump pays for itself will depend on how much you run the pump. Technically, you may only need 3 hours per day at that flow rate to turnover the pool once per day but most people will run the pump longer to have circulation during the day and run the cleaner. Also, total savings will depend on how much time that you run the pump at lower speeds vs higher speeds.

[PoolDoc]

Mark, I just emailed you.

Thanks for the post.

Ben

[djcjdad]

Hi Ben and Mark,

Thank you so much for the prompt replies. They were both very helpful. After furter inspection my pump is a Hayward RS 1500 1.5HP or 2.0THP. After I had it replaced about 1.5yrs ago the power bill went up (1/4 to 1/3) immeadiately, leading me to believe that the pool guy installed to big of a pump. However, like I said before my old pump was a pentair and a 1.5hp. Having said all of that this pump from day one had a lot of turbulence at the pump basket until he diverted a lot of that flow away from the caretaker side of the T valve and instead moved more water through the 3 returns in the top of the pool. Weird, I never had this problem before he installed the new pump. I still wonder if its to big. Besides the one station with 6 heads...all the rest of the stations have 3 or 2 heads. Is there anyway I can get around this issues with the in-ground cleaning system being a power/PSI hog? I know eveyrbodys pool is different, but I was thinking maybe if I bought a new Hayward Ecostar I could run the pump at or close to top speed for a few hours(3-4) a day and then back it down to a much lower RPM for just circulating the water and chems through the filter. My pool is 2" plumbing with a Hayward pro series sand filter model # S244S.

Once again thanks for the advice.

Jeff

[mas985]

Is there anyway I can get around this issues with the in-ground cleaning system being a power/PSI hog?

The heads need a certain flow rate and pressure so there really is no way to get around that.

I was thinking maybe if I bought a new Hayward Ecostar I could run the pump at or close to top speed for a few hours(3-4) a day and then back it down to a much lower RPM for just circulating the water and chems through the filter.

That will help to reduce your energy consumption but another option would be to swap out the current motor for a two speed motor and do the same thing. Also, if you wanted to, you could just stick with the single speed and run it for 3 hours per day since that is at least a single turnover. That could be enough. If not, then a the VS or two speed is a good option.