Replacement of 1 HP 1- speed motor with a 2-speed motor - PLEASE ADVISE

[Jaro]

Last week, I put a post on the Forum entitled ‘Upgrading single speed Super Pump to 2-speed or VS‘ but haven't got any useful response; perhaps because of a too detailed description of my issue. So, I wonder if you would kindly respond to a more direct question below.

Present situation: Present pool equipment is described in my signature (21K gal, IG plaster new 2010, 1 HP Super Pump, sand filter S-244T2, solar heating with HM-4000D controller, Hayward Cl Feeder CL220). This season, I am operating Hayward Super Pump with 1 HP single speed motor 24/7 because in the past I had to brush periodically green algae from the pool walls when operating it just 12 hrs a day.

Issue: To minimize electricity cost while providing flow rate needed for effective sanitation, I am considering a replacement of the present 1 HP single speed motor with an appropriate 2-speed motor.

Using the guidance found in Pool Pump Sizing and Super Pump performance data, I estimated the Total Head Loss and associated flow rates for Super Pump with 1 HP motor.

(a) w/o Solar heating: Total Head Loss 40 ft 54 GPM at 3450 RPM 27 GPM at 1725 RPM
(b) with Solar heating: Total Head Loss 50 ft 40 GPM at 3450 RPM 20 GPM at 1725 RPM

Based on the above, I am thinking to get from Electric Motor Warehouse a Century motor B2975T
1hp 3450/1725 230 volts 56J Pool Motor w/intergrated timer

Question: Does the above motor selection make sense? Please let me know. Thank you.

Jaro Pachner

 

[mas985]

To minimize electricity cost while providing flow rate needed for effective sanitation, I am considering a replacement of the present 1 HP single speed motor with an appropriate 2-speed motor.

Any pump or speed will accomplish that. It doesn't take much to circulate chlorine. The power of the pump is for other things such as spas, waterfalls and to a lesser degree skimmers and cleaners.

But the B2975T is a full rated motor and it is a larger diameter than your current motor. The 1 HP Superpump uses an up rated motor. The motor you really want is the STS1072RV1. It is a full rated 3/4 HP but is the same "size" as a 1 HP up rated motor. It is also the correct diameter.

 

[Jaro]

Many thanks for your reply. I will need sufficient power to push water through my solar heating mounted on the roof (Total head loss 50 ft.) jaro

Any pump or speed will accomplish that. It doesn't take much to circulate chlorine. The power of the pump is for other things such as spas, waterfalls and to a lesser degree skimmers and cleaners.

But the B2975T is a full rated motor and it is a larger diameter than your current motor. The 1 HP Superpump uses an up rated motor. The motor you really want is the STS1072RV1. It is a full rated 3/4 HP but is the same "size" as a 1 HP up rated motor. It is also the correct diameter.

 

[mas985]

Many thanks for your reply. I will need sufficient power to push water through my solar heating mounted on the roof (Total head loss 50 ft.) jaro

Again, most any pump will do that. I have a 1/2 HP pump running solar on a two story roof. No Problem.

But understand that increasing the size of just the motor does nothing. It is the impeller that determines the size of a pump, not the motor. Of course the motor needs to be sized correctly for the impeller or it could overheat. Anyway, the correct two speed motor for your pump and existing impeller is the STS1072RV1.

 

[Jaro]

Thank you for clarification. Jaro

Again, most any pump will do that. I have a 1/2 HP pump running solar on a two story roof. No Problem.

But understand that increasing the size of just the motor does nothing. It is the impeller that determines the size of a pump, not the motor. Of course the motor needs to be sized correctly for the impeller or it could overheat. Anyway, the correct two speed motor for your pump and existing impeller is the STS1072RV1.

 

[Jaro]

Mark,
I am back from the cottage and following up on your advise re replacement of a current 1 HP single speed motor CT1102 with a dual speed STS1072RV1. STS1072RV1 is a 2-speed motor but w/o a timer.

Since I'd like to operate the Super Pump on high speed about 10h/day and on low speed 14h/day, I will need a timer to provide for such operation.

One possibility is a 3/4 HP Full Rate Two Speed Motor with integrated timer - Round Flange (B973T, B2973T) 115V; web link A.O. Smith 3/4 HP Full Rate Two Speed Motor W/ Timer - Round Flange (B973T, B2973T) 115V - INYOPools.com

This motor is larger in body diameter - 6.5”; I'd have to remove the mounting foot adapter underneath the motor. One question is the reliability of the integrated timer.

I'd be grateful for your comments on B973T and also on a possible timer for STS1072RV1. Thank you.

Jaro

Again, most any pump will do that. I have a 1/2 HP pump running solar on a two story roof. No Problem.

But understand that increasing the size of just the motor does nothing. It is the impeller that determines the size of a pump, not the motor. Of course the motor needs to be sized correctly for the impeller or it could overheat. Anyway, the correct two speed motor for your pump and existing impeller is the STS1072RV1.

 

[mas985]

I really don't have any experience with those timers but my guess is it should out last the motor.

Sent from my SM-G900V using Tapatalk

 

[Jaro]

UPDATE and a follow-up question for Mark (mas985).

A couple of weeks ago, I replaced 1 HP motor by an A.O. Smith 2Green 3/4 HP Full Rate Two Speed Motor with integrated timer - Round Flange (B973T, B2973T) 115V. It was a good fit after removing the 'mounting foot adapter' from the Super Pump mounting foot. The timer interface is user friendly.

Mark, I wonder if you could offer advise on optimum High Speed and Low Speed timer settings taking into account circulation requirements; consideration of electricity rates is secondary (Low: 7pm - 7am; Mid: 7am - 11am, 5pm - 7pm; High: 11am - 5pm). Thank you.

 

[mas985]

That is waaaay too much run time. Any reason you think you need that much. Have you read this: Pool School - Determine Pump Run Time

For reference, my pool is about the same size as your and I run my pump for 1 hour on high (just for the cleaner) and 3 hours on low speed (mainly for the SWG and solar). And even that is too much run time.


But what is "Mid" for a two speed motor?

 

[bignick]

I took the low-mid-high times to be the electricity rates. If so, unfortunately the best time for solar heating is at the highest rates.

 

[mas985]

I would just run it for solar. You shouldn't need anymore run time than that.