Two speed pool pumps

Two speed pool pumps

PostBy: djackman On: Sun Aug 02, 2009 12:03 am

Anyone use / have one? Experiences?

I picked one up for a song at a garage sale and am thinking about switching mine out.
djackman
 
Stove/Furnace Make: 1980 vintage Tarm
Stove/Furnace Model: FT22 (aka 202) installed!

Re: Two speed pool pumps

PostBy: Kenbod On: Mon Aug 03, 2009 12:38 am

I went from a single speed 1hp to a variable speed pump and cut my costs significantly.

I have a 27kgal pool with twin 2" returns and supplies. The 1hp drew 1.8kw/hr (about $0.27) and most of that energy went to overcoming pump resistance and dynamic head. I tried a timer, but to keep everything clean and sparkly I need to run it at least 15hr/d, sometimes 24h/d. Anyway, it was always over $100/mo.

The new pump is very different: high end seals, bearings, windings, electronics. Depending on filter cleanliness, it draws 350-500w when dialed down to 25 gal/min. We're talking about $50/mo.

I save $50-75/mo, about $250/yr. It allowed me to plumb in a chlorinator which can now run 24/7 with very good control. We actually went away last week and came home to a clean pool! (First time ever.)
Kenbod
 
Stove/Furnace Make: Van Wert Simplex Multitherm
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Re: Two speed pool pumps

PostBy: 009to090 On: Mon Aug 03, 2009 7:33 am

Kenbod wrote:I went from a single speed 1hp to a variable speed pump and cut my costs significantly.
I save $50-75/mo, about $250/yr. It allowed me to plumb in a chlorinator which can now run 24/7 with very good control. We actually went away last week and came home to a clean pool! (First time ever.)


OK, I'm sold too! Never heard of them. What brand do you have? Does Hayward make them?
009to090
 
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small pump, big filter and pipes

PostBy: eelhc On: Mon Aug 03, 2009 8:41 am

The best combination is a small or multi speed pool pump combined with a large/oversized filter and big pipes. Idea is to keep the flow rate up, pressure down and pump running less harder/hotter.

2 Speed pumps can be expensive (as expensive as a larger/oversized filter). My preference is to get the bigger filter first and run the pump on a timer. My 1hp pump runs 8~12hrs/day and is timed to come on/off 3 separate cycles. Also... if you can help it, wire the pump for 220V operation which is a simple way to save $$$ on electricity.

One should depend on the pump/filter to filter the pool but not to sanitize it.

http://www.troublefreepool.com
eelhc
 
Stove/Furnace Make: Harman Magnum Stoker

Re: Two speed pool pumps

PostBy: Bob On: Mon Aug 03, 2009 9:08 am

Variable speed pumps are expensive to buy--$800 to $1000 but they do dramaticly cut operating costs in most situations. The savings come from two sources:
1. Most, if not all, variable speed pumps are actually 3 phase motors with the appropriate electronic controls to allow them to operate from single phase power and to vary speed. 3 phase motors are significantly more efficient than single phase motors; and
2. Operating at lower flow rates dramatically reduces power requirements beause power increases with the square of flow.

In my application I was using a high quality 1/2 horsepower single speed pump that drew nearly a kilowatt. I replaced it with a variable speed pump (with a max hp rating of 3) and now operate at about 150 watts.
Bob
 
Stoker Coal Boiler: AHS 130
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Re: Two speed pool pumps

PostBy: djackman On: Mon Aug 03, 2009 5:55 pm

It's only been a day or two and I'm sold. If the math right it's flowing ~30gpm on low speed.

Pump back-pressure is now 5psi vs 20psi! 1.75a draw vs 5.6a (240v) on the old 3/4hp motor.

This is an older pool inground vinyl 23k/gal pool with 1.5" supply/return, if lines weren't are under concrete apron I'd upsize them
djackman
 
Stove/Furnace Make: 1980 vintage Tarm
Stove/Furnace Model: FT22 (aka 202) installed!

Re: Two speed pool pumps

PostBy: Kenbod On: Mon Aug 03, 2009 8:55 pm

This is why this forum is great: good people sharing real experiences and academically correct info! :D

1. Multi speed pumps, especially high end ones, work as described above with superior windings, seals, bearings, and 3-phase electronic convertors. But they are crazy expensive.
2. Up-sizing the plumbing is key (but not helpful in existing pools). Up-sizing the filter helps a lot (but some filter/pump combos need a minimum back-pressure. Cartridge filters don't have this requirement). Most of the wasted energy in most pools comes from "dynamic head" (friction resistance) followed by pump design.
3. Return on investment is best with the smallest pump running 24/7 with the biggest filter and plumbing. Any simple pump so configured to do 1 turn over per day will be the cheapest long term option.
4. Unless one does careful static/dynamic/pump calculations, it can be hard to know exactly what pump to buy. I know that I had the wrong pump for 5 years! Bigger is not better (too much dynamic head = wasted energy, accelerated wear on pump and plumbing) and too small can be worse.
5. A variable speed pump, even if only used during initial set-up, can give you all the dynamics of the pool. You could then just buy the pump you really need. A word of caution: most pools will be fine with pumps which traditionally would be considered "too small" but they are very hard to find. Thus the variable speed pumps.
6. The pool described above, even with the new pump, probably still has more flow than needed as 30gpm should give 2 turn-overs per day. You might consider a timer too.
7. MY pump is a Pentair IntelliFlo (3.2kw, Variable). It was CRAZY EXPENSIVE at over $1000. However, I am crazy. My pool has a salt water generator, a roof top solar heating system, a lilly pad (kinda like a Jacuzzi, sorta), and an air source heat pump. Under differing conditions (such as automatically directing the water to the roof top collectors), I needed a pump that could vary speed to maintain a set gpm output. There are lots of fancy controls out there, some pretty complex, some not compatible. Or, one could just connect the IntelliFlo and read the owners' manual. Yep, it can do all that right out of the box. No required add-ons or gizmos. :dancing:
Kenbod
 
Stove/Furnace Make: Van Wert Simplex Multitherm
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Re: Two speed pool pumps

PostBy: djackman On: Mon Aug 03, 2009 11:27 pm

I'd tried a two-speed pump a few years ago with poor results, flow rate just wasn't there. What made it work this time is a Hayward "Super II" pump body instead of the classic "Super Pump". The low speed GPM is nearly double on the Super II, they've made big improvements in pump efficiency.

There's a general ignorance in the pool service industry of pump sizing, bigger is always better. Thankfully spring & fall pumps are plentiful in the trash here, manuals & parts easy to get, not complicated to rebuild. Originally came with a 2hp motor set on 120v, 24/7 runtime, single 1.5" return, 30psi on clean filter :shock: There was 10/3 service to the pump pad. :roll: (previous owners must have been shareholders in the power company).

Installed a timer and 1hp/230v trash-night special pump in the first week of operation. Stepped down / upgraded as equip showed up.

Removing the return flow directors in the pool was good for a 3 psi reduction on the 3/4hp pump I was using until this weekend. Thinking of putting them back in to help better distribute the new low pressure return water thru the pool.

Thanks for comparing notes
djackman
 
Stove/Furnace Make: 1980 vintage Tarm
Stove/Furnace Model: FT22 (aka 202) installed!

Re: Two speed pool pumps

PostBy: Yanche On: Tue Aug 04, 2009 7:51 am

I don't have a pool or have any experience with pool pumps. But clearly the critical design parameter is the resistance to flow (pump head) created by the piping and filter. If you know the pump curve of your existing pump, i.e. the manufactures curve of head vs. flow rate you can determine the flow resistance. It's done by putting a pressure gauge on the inlet and outlet of the pump. With these readings and the pump curve you know the flow rate. Then you can select the correct pump and/or make upgrades to lower flow resistance. Pump selection doesn't have to be a guess.
Yanche
 
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Re: Two speed pool pumps

PostBy: Kenbod On: Tue Aug 04, 2009 9:44 am

Yanche is correct about about hooking up any pump to a pool an measuring return "vacuum" and and system "pressure". The rules of fluid dynamics apply regardless of whether you're dealing with a boiler loop or a pool.

However, pool boys are far less knowledgable than boiler technicians. In my experience, there is no comparison.

Consistent with Yanche's points, if you don't have accurate calculations based on your pool's design, you only have two choices: guess or test. Pool boys almost always "guess" based on pool size. The other choice is to test using a pump with a known curve. Or just start with a variable speed pump.

My IntelliFlo (crazy expensive- see my post above) has a huge range of variablity and can display flow across the range. In essence, it has multiple pump curves. A "test" with a pump operating along a fixed curve gives data for that curve. But dynamic resitance will vary impressively as one pushes harder and harder.
Kenbod
 
Stove/Furnace Make: Van Wert Simplex Multitherm
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