Questions for Mark

[kevreh]

Hi Mark;

I saw your specs in your signature as;

"18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater"


That gave me pause as a 1/2 HP pump for a 20k pool AND filter AND Solar Panel (on the 2nd story, mentioned in a thread) seemed very underpowered. I currently have a system somewhat similar to yours (specs below) and am considering a 2 speed pump, downgraded to 3/4HP. I have a 1HP Superpump now and am wondering if I should replace it and if its worth it $ wise.

Questions;

- Do you have a problem running low speed through your solar panels, and do you have a method to start the pump on high to get the system going then switch to low? I have a Suntouch controller that can start the pump on high speed initially then switch to low speed after 5 minutes.
- Is a pumps rate and efficiency dictated by the housing, motor, or both. I could get an replacement motor (http://www.poolcenter.com/motor_parts.htm) thats' 2 speed and 3/4HP for under $300. But would that replacement motor be as good as a Superflo or Whisperflo (I like the Pentair brand, lol).
- Can I take a 1HP Superpump and put in a 3/4HP 2 speed motor, or does it have to be a 1HP motor?
- How much power do 2 speed pumps save? [edit: I think I found the answer (about 1/2 the flow and 1/4 the power)]

My Specs;

- 16x32 plaster pool, est. 24k gal.
- Hayward Superpump, 1HP, a few years old
- Pump pad is about 4' above pool waterline
- 1-1/2" plumbing to/from pump
- Pentair Suntouch Controller
- 36sf DE Filter
- 2- 4x12 Solar Panels, 2nd story


Thanks!
Kevin

 

[linen]

If it is a 1/2 hp whisperflo for example, it will move more water than say a 1 hp superpump. You really need to look at the curves, hp does not tell much.

 

[msgtdan]

Keep in mind that if you drop the motor h/p below the pump rating you'll need to change the impeller to match.

 

[mas985]

Hi Mark;

I saw your specs in your signature as;

"18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater"


That gave me pause as a 1/2 HP pump for a 20k pool AND filter AND Solar Panel (on the 2nd story, mentioned in a thread) seemed very underpowered. I currently have a system somewhat similar to yours (specs below) and am considering a 2 speed pump, downgraded to 3/4HP. I have a 1HP Superpump now and am wondering if I should replace it and if its worth it $ wise.

First some background. My pump is a bit of a mishmash. It has the wet end of a 1/2 HP Northstar and the motor of a 1 HP Superpump. I call it my FrankenPump. The head curves for a 1/2 FRHP Northstar and a 1 URHP Superpump are about the same which is why I could use the Superpump motor on the Northstar. So the pump isn't really as small as it appears.

- Do you have a problem running low speed through your solar panels, and do you have a method to start the pump on high to get the system going then switch to low? I have a Suntouch controller that can start the pump on high speed initially then switch to low speed after 5 minutes.

I don't run solar on low speed because low speed does not generate enough pressure to keep a VRV closed when it is installed on a two story roof. I could have lowered the VRV to allow low speed but my controller only allows high speed during solar demand periods.

- Is a pumps rate and efficiency dictated by the housing, motor, or both. I could get an replacement motor (http://www.poolcenter.com/motor_parts.htm) thats' 2 speed and 3/4HP for under $300. But would that replacement motor be as good as a Superflo or Whisperflo (I like the Pentair brand, lol).

Primarily it is the impeller that determines the head curve of the pump and thus how much energy the motor will draw. The diffuser and volute also contribute but those are usually fixed for a particular pump line and only the impeller and motor is changed for different "sized" pumps.

- Can I take a 1HP Superpump and put in a 3/4HP 2 speed motor, or does it have to be a 1HP motor?

It is the impeller that determines the shaft load and the power required from the motor. So the motor must be sized for the impeller. However, the motor can be bigger than what is called for, just not smaller.

- How much power do 2 speed pumps save? [edit: I think I found the answer (about 1/2 the flow and 1/4 the power)]

Correct, if you compensate for the flow rate, a two speed will save a little over 50% of the energy costs.

 

[kevreh]

Thanks mark.