SWG and two speed 2 HP motor conversion

[MSPT3K]

It looks like about a 9 month payback on installing a two speed motor in place of my existing 2 HP motor at $0.10 or so a kwh. My concern is whether this is likely to cause flow switch problems with my Hayward Aquarite. I've got 2" plumbing and the pad is about 15' from the pool. Motor is likely oversized for normal pool operation, but nice when you turn the waterfall on. $500 wasted if I have to keep it on high to use the SWG. Seems likely to work as I read of lower HP two speed conversions and the flow switch for Hayward looks to be the same regardless of salt cell size.

Anyone know with reasonable certainty whether the two speed A.O. Smith B2984 at low speed will push enough flow to keep the flow switch active? Any recommended impeller changes?

Thanks in advance!

 

[JamesW]

What's the filter pressure?

 

[MSPT3K]

13 psig. Removed filters, hose cleaned, and put 6 lb DE in last weekend.

 

[JamesW]

It should work.

The flow switch requires a minimum flow rate of 11 gpm to stay closed consistently.

Low speed should do well above that.

 

[MSPT3K]

Thanks!

Very good forum, I've learned a lot from reading here. Just signed up as a supporter.

 

[JamesW]

Thanks for your support.

 

[MSPT3K]

Final report - success!

This morning I installed the new motor and switch box. Works great! Hayward flow switch is happy on low flow. I'll run it on high for an hour at startup in the morning for the extra skimmer flow. Super quiet on low, an extra benefit. Filter pressure on low is just a few psig.

Old motor: 10.8A (as measured)
New motor: 10A, 2.2 A (as measured)
8.6 amps savings over 10 hours/day = 570kWh per month, at my roughly $0.10/kWh that's $680/year.

New motor: $350 Centurion 2 HP- 1/4HP motor from Sunplay pools.
Intermatic switch box for high/low on a separate timer from existing on/off timer from Amazon: $100
Conduit and wires: $30
New pump seal kit: $20

Total: $500 spent. Fairly easy installation if you are ok with home wiring, took me a few hours total including pump re-seal and reattach. Worst part was figuring out the wiring and choosing colors.

Payback: 9 months. Wish I'd done it 15 years ago.

 

[JamesW]

Good job. Thanks for the update.

 

[Philo]

Great savings!
Imagine the savings in San Diego at $.40/Kwh

 

[peirek]

Hello MSPT3K,
Can you provide the link to the "Intermatic switch box for high/low on a separate timer" please?

INYO Pool Install info: How To Install a 2-Speed Motor and a T106 Timer - INYOPools.com

Intermatic T106 Timer: https://smile.amazon.com/Intermatic-T106R-24-Hour-40-Amps-208-Volt/dp/B003A20SZM/ref=sr_1_1?ie=UTF8&qid=1522769428&sr=8-1&keywords=Intermatic+T106

 

[MSPT3K]

The Intermatic T106R is the "high/low on a separate timer". It only allows either the high or low speed to be selected - not both at the same time, which would be very very bad.
The on/off timer for the pump is an existing T104 originally installed to turn the single speed motor on and off. It sends power to the 106R contactors for the time periods you want the pump on (either high or low).

Attached is how I wired them, I referenced the INYO article also. I made a reference drawing to put in the box.




I suspect the automation systems handle this more elegantly than two mechanical timers, but they are simple and cheap components. Timer motors burn out, but won't break the bank to replace.

 

[peirek]

I hate to hang another box but short of doing my own timer and relay assembly I have not found a solution other than this.
Thanks for taking the time to document.