narrowing pump choices, please critique

[mr ken]

I was set on getting a Pentair whisperflo....mas985 feel that I have about 60 ft of head and the 1/2 hp whisperflo would give me about 55 GPM....(mas 985 thank you for all your expertise )

I have 1 1/2 inch pipes so GPM is an issue....

My question today is that many prefer the dual speed pumps because the can be run on a very low HP, flow rate and conserve energy and money....

Today I called Pentair/Sta Rite to ask about the Dura Glas pumps...........

The Dura Glas up rated 1/2 hp, according to Pentair, puts out 30 GPM at 60 ft. of head, and 35 GPM at 50 ft. of head....

The Dura Glas up rated 3/4 hp, according to Pentair, puts out 40 GPM at 60 ft. of head, and 50 GPM at 50 ft. of head...

It I got the 1/2 hp at 30 GPM at 60 ft of head, would it be efficient enough for my pool and would it not be similar to using a dual speed set on low...

Pool is 9,500 gal. 1 suction line and 2 return jet lines and 1 1/2 inch pipe...

Would that work and is Dura Glas a quality product ?
Thanks
Ken

 

[randytsuch]

I was set on getting a Pentair whisperflo....mas985 feel that I have about 60 ft of head and the 1/2 hp whisperflo would give me about 55 GPM....(mas 985 thank you for all your expertise )

I have 1 1/2 inch pipes so GPM is an issue....

My question today is that many prefer the dual speed pumps because the can be run on a very low HP, flow rate and conserve energy and money....

Today I called Pentair/Sta Rite to ask about the Dura Glas pumps...........

The Dura Glas up rated 1/2 hp, according to Pentair, puts out 30 GPM at 60 ft. of head, and 35 GPM at 50 ft. of head....

The Dura Glas up rated 3/4 hp, according to Pentair, puts out 40 GPM at 60 ft. of head, and 50 GPM at 50 ft. of head...

It I got the 1/2 hp at 30 GPM at 60 ft of head, would it be efficient enough for my pool and would it not be similar to using a dual speed set on low...

Pool is 9,500 gal. 1 suction line and 2 return jet lines and 1 1/2 inch pipe...

Would that work and is Dura Glas a quality product ?
Thanks
Ken

Mark is the expert at this stuff, not me, but I will give it a shot.

A two speed pump runs at, two speeds (duh), 3450 rpm, and 1725 rpm.
A smaller one speed pump is running at 3450 rpm, it is just that the front end is designed to move less water. Basically, I think the impeller is smaller, so while a 1/2 hp or a 3 hp will both run at 3450, the 3hp will have bigger impellers, so it can move more water, to also have a higher head capability.

Two speed pumps save money by letting you run at 1725 rpm's. At this lower RPM, the water moves slower, and there is less energy loss to friction. In Mark's thread on pumps, it says that low speed head = high speed head / 4.
So, at low speed, your head goes down to maybe 15, and the pump is much more efficient.

As for your pool, at 9500 gal, to get one turnover in 8 hrs, you only need 20 gpm flow rate. 1.5 inch pipes can handle up to 42 gpm. That's why you don't need a big pump, your pool is smaller, so you don't need a high gpm.

So, I would think the 1/2hp at 30 gpm is fine, but it's not the same as running a dual speed pump at low speed.
You might consider getting a electrician to quote how much it would cost to hook up the pump with 115VAC.

Randy

 

[JasonLion]

A very small pump may not vacuum well. It may also have trouble priming if the pump is too far above water level.

A two speed pump on low is 1/8th the HP on low speed. High speed let's you vacuum and prime without problems and low speed will save you money even over a smaller pump.

 

[kamoo]

The 2sp on paper will save you energy on low speed at any size in the Dura-Glas
DuraGlas 2sp @ 1.16 = 598w/1679w, 1.5 = 575w/2116w, 2.3 = 651w/2323w at low/high spd
1/2hp = 1150w
3/4 = 1541w
Obviously if it takes twice as long to do a water turn with the 1.16 2sp on low as the 1/2hp, you will be equal. Youll have to figure the flow and all other variables into this for it to make sense.

 

[JasonLion]

A two speed on low uses about 1/3 the power and moves exactly half as much water. So even running twice as long that is around 2/3 the electricity. The power savings varies from pump to pump as you can see from the numbers previously posted. Some of those pumps will save even more