Variable Speed Pump VS 3050---gpm/rpm?

[oroepke1]

Hi everybody,

I am relatively new here since I only enjoyed my new pool (SWG, 12000 gal inground gunnite) for about a month or so. When the pool company did the start-up they had me run the 3 hp pump 24/7 on full throttle and after a week reduced it to 4 hours at 2900 rpm and 16 hours at 1500 rpm. Do I really need to run it that much? And can anybody tell me the gpm/rpm? I know this is dependent somehow on where the pump is located, in my case it is on the water surface level at about 20 feet away from the pool. I have heard that I don't need to turnover the pool more than twice a day in summer (we are very heavy users though..).

Thanks a lot and BTW I did NOT get poolstored during my first poolstore visit, thanks to what I have learnt from here :)

Olaf

[Poconos]

Hi Olaf,
with that pump seems like they have you running in overkill mode. There is a graph on page 32 of the users manual

http://www.pentairpool.com/pdfs/IntelliPro4x160OM.pdf

that shows GPM vs RPM vs head. If you look at just the 1500 RPM line and assume not much flow resistance you're probably doing 40 GPM minimum. That's over 38000 gallons on just that speed. Cut it way back and save $$$. The 2X exchange per day is probably a good number. Curious what kind, type, model filter you have. On the high speeds you could easily get into the big pump small filter problem.
Al

[oroepke1]

Thanks, I had seen that graph but what is my TDH? I don't want to go through all the formulas.....:)

I have a DE 100 filter and also a Ozonator and they told me for the ozonator to work right, I need the high flow, does that make sense?

[lbridges]

Do you have automation, such as an Easytouch system? THat makes flow rates much simpler as there is a spreadsheet that relates RPM and Wattage to determine flow rates.

[chem geek]

Thanks, I had seen that graph but what is my TDH?
TDH is Total Dynamic Head, usually expressed in feet (of water). Dynamic head is the resistance (pressure) associated with water flowing in pipes and through inlets/outlets. Static Head is pressure associated with an elevation difference though usually this is canceled out between the suction and pressure sides of the pump. Static head is more relevant for whether you can prime the pump or to raise water to a solar panel on a high roof.

[oroepke1]

Yes I have an Easytouch System, but haven't played much with it since I spent all of my available time in the water:) I guess I will dig into the manual sometime soon .....And thanks for the explanation of static and dynamic head!

I am sure I will be back with questions soon, this is a GREAT forum, thanks!

Olaf

[mas985]

There are a couple of ways to get to GPM for the Intelliflo. If you know the wattage that the pump is drawing, the link labeled "Pump Modeling Tools" in my signature, there is a spreadsheet which relates GPM, RPM and watts.

If you don't have a power reading then I can make guess for you based on some additional information.

Pipe size and number of runs pool to pad for both suction and return.

Filter PSI at a given RPM, preferably at a higher RPM.

[Searcher]

Hi Olaf,
with that pump seems like they have you running in overkill mode.


Wow, understatement of the year. lol

When I see pool people dump their excess motors on an unsuspecting customer and then blow smoke about ozone, it makes my blood boil.

This is from their site...

"Balance water chemistry, shock, and use a sanitizer system. Ozone reduces the amount of chemicals needed and improves water quality, but will not replace your sanitizer."

With that, why bother at all? Use BBB, save, save, save and have much cleaner water.

There is no way, no how that a 3 HP motor should be any where near a 12K gallon pool. The "installers" probably piped it out with 1 1/2 inch pipe as well. Sigh!

I would have them replace the motor with a 1 HP - 1/6 HP, dual speed motor and take their ozone away with that monster 3 HP motor.

Getting off my soap box now. :(

[mas985]

The Intelliflo is both a variable speed pump as well as a variable HP pump. Changing the speed, changes the braking HP of the motor. So in effect, it can emulate any pump on the market at any speed and usually, at better efficiency. While it is true that top speed is the equivalent of a 3 HP pump, nobody said that it ever needs to be run that high and it was probably not necessary during the start up.

[oroepke1]

Not sure how I can quote from another email but this was from "Searcher"
""There is no way, no how that a 3 HP motor should be any where near a 12K gallon pool. The "installers" probably piped it out with 1 1/2 inch pipe as well. Sigh!"

I have to defend my PB somewhat. I opted for a larger pump and to run it at lower speeds since I was told that makes sense. I also have a water shear that looks really nice at 80% of full throttle 3hp :)

My goal is to run the pumps less, but since I don't know much about the pool yet I decrease runtime gradually and the input I received here is very helpful.

BTW I used this formula that I found somewhere to calculate head: (2.31 *filter psi + 3)*1.25
(1.25 is for 25% friction loss, since I have 2 and 2.5 inch pipes, 3 is added since the filter is 3 feet high).

(2.31*4+3)*1.25 ~15 feet (1500 rpm) from chart: 40 gpm
2.31*12+3)*1.25 ~40 feet (3000 rpm) from chart 120 gpm

Does the math make sense? Thanks again for all the help!

Olaf

[mas985]

That was probably one of my formulas but the flow rate is fairly high for the RPM.

Running through my model I get about 107 GPM at 44 ft of head. 1500 RPM is half of that or about 53 GPM. Flow rate will always be proportional to RPM unless you have check valves, then it tends to drop faster with RPM. I assumed 35' runs and only one 2.5" suction line and one 2" return line plus typical equipment.

[chem geek]

From my numbers (http://www.troublefreepool.com/calling-all-pool-owners-tell-me-about-yours-t1713-20.html#p25669) for my IntelliFlo VF, with solar off I have 1500 RPM with around 25 GPM at 4-5 PSI (9-12 feet) while at I have 3000 RPM with around 70 GPM at 18 PSI (42 feet), but my pressures do not include suction head and I have somewhat long pipe runs (2" pressure-side; two 1.5" suction side).

[Poconos]

I do realize that pump can operate at any speed. However the thing I would be concerned about is the electronic complexity of the thing. A two speed motor is just another set of windings and a switch but when you get into continuously variable speed motors you have a lot of electronics involved and it operates in a relatively harsh environment to boot. Granted the reliability of the electronics has gotten very good, especially in the automotive underhood environment which is extremely harsh from a thermal standpoint. However, the pool environment is harsh in some ways too, namely power line spikes and lightening. I also realize there are lots of electronics in the home today that survive spikes quite well. Just my comments. I believe simpler is better. I think once you get to know your pool you can settle in on runtimes and speeds that will work no matter what the math says.
Al

[chem geek]

Personally, if one can afford the IntelliFlo VF pump, I'd go for it. I love mine and there is no way that I could have tuned my system as well as I did with a standard 2-speed pump. The savings I get when the solar system is on by running at 48 GPM instead of the 55 GPM with my previous fixed-speed pump is considerable while the savings I get with the solar off running at 26 GPM with the IntelliFlo compared to a 2-speed pump that might have been at around the same speed is also considerable.

If one cannot afford a variable speed/flow pump, then a 2-speed pump is still much better than single speed and will still save a lot in energy costs -- just not as much savings.

[mas985]

All true except that you really need to look at the lifetime costs of each solution and not just the energy savings. While the Intelliflo does better for energy usage, the cost premium, interface panels and/or controllers can make the 10 year cost higher for the Intelliflo than a 2 speed. So it really depends on the situation. Of course if you are only worried about carbon credits, then the Intelliflo is certainly the most ecological solution. :D