Why is my PB tying to talk me out of 2 speed?

[mas985]

The numbers don't lie.

Not sure what pump you are considering so I will use a Whisperflow as an example.

Assumptions:

1.5 HP Whisperflow full rated 2 speed pump: http://www.poolplaza.com/WhisperFlo-techspecs.shtml
8.8 amps single speed pump (2.0 kw)
10 amps high speed two speed pump (2.3 kw)
3.5 amps low speed two speed pump (0.8 kw)
60 feet of head loss on high speed
15 feet of head loss on low speed (1/4 of high speed)

Results:
High/Single Speed flow rate = 100 GPM
Low speed flow rate = 50 GPM
High/Single Speed turnover = 5 hours
Low speed turnover = 10 hours

Assuming 2 turnovers per day and 30 days in the month,
Single speed energy usage per month = 600 kwh
High speed energy usage per month = 680 kwh
Low speed energy usage per month = 480 kwh

Energy usage difference between single and low speed is 120 kwh per month. Depending on your rates, mine are quite high, this will add up. At $0.20 per kwh, my average rate, this is $24 of savings per month. Assuming a two speed is $200 more than a one speed, the pay off is in less than 9 months. Even if your rates are half of mine, that is still only 18 months.