Variable Speed Pump

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user_unknown

user_unknown

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Apr 21, 2014
8
Metro Phoenix Arizona
Is replacing a single speed pump with a variable speed pump worth it if our electrical cost is .07 per kWh? The Pentair website seems to think so but I wanted other opinions.
I currently have a Hayward 2HP super II on a 60sf Hayward D.E. Filter with a suction cleaner and I am contemplating upgrading to an Pentair Intelliflo VS pump to reduce electrical consumption.
I am on a time of use plan with our electric provider and our on peak cost is 19-21 cents per kWh and 7 cents kWh off peak, obviously I run the pump only off peak.
I currently have absolutely no issues keeping the pool clean, the suction cleaner gets it done in an hour or two unless there is a storm. I am currently running the pump 8 hours per 24 hours(this may be too much)
 
Personally, I'd try knocking a couple of hours off the current run time and see how it goes. Then when it's time for a new pump, think about a variable. It would give you some options such as solar heat since it wouldn't be insane to run it during the high rate times of the day. The savings isn't huge. You are probably spending about $300 a year for the pump now.
 
It may make sense for you to replace your motor with a 2 speed motor. You are now spending around $35 per month for 8 hours of pump time. You probably could drop that to around 4 hours and be okay, which would put you at around $18 per month.

Or you could get a two speed motor, which would drop you to around $7 per month with an 8 hour run time. You could also maybe drop your pump run time to 6 hours or less, which would get you to around $5 per month or less. It would cost you close to $340 to get a two speed motor (plus installation cost). The payback assuming $400 investment and monthly savings of $13 (based on 18-5) would be about 26 months. The variable speed motor will have a much longer payback period. If you ran on peak the payback would obviously be much faster.

If it were me, I would keep running the existing motor for fewer hours per day, and when it goes out replace it with a two speed motor.
 
I too would lean towards 2 speed pump and run in off peak hours on low. If the wet end of your current pump is still in good shape it is easy enough to swap in a 2 speed motor in place of your single speed, this is a 20-30 minute job and the plumbing does not have to be touched. Price will be about 1/3 of new a variable speed pump, and electrical savings will be almost as much.
 
What are the typical speeds on a two speed pump? Also, I suspect that the current 2HP is too much, pool builders in this area are notorious for oversizing everything.

My current set up is the 2HP Hayward super II on 60SF Hayward D.E. Filter, no spa, separate plumbing/pump for water feature, equipment is approx. 65' from pool, 2" suction, 1.5" return line, suction cleaner. 1.5HP would probably be fine.
My current pump is still operational, it is original circa 1996 but I have the motor rebuilt every 3-4 years when it craps out.

My pool previously was a salt water pool but I had the pool refinished and the contractor asked me not to convert it back to salt for at minimum 90 days, preferably 6 months. I had forgotten how easy it is using liquid chlorine, I may never go back to salt.
 
Two speed pumps draw 1/4 power on low and move about 1/2 as much water as on high. So in your case if you were to just do a motor swap you would have a 2 HP high speed setting for vacuuming, backwashing,etc. and a 1/2 HP low speed.

Ike
 
You are right, your pump is much bigger than needed. I have a 1HP 2-speed or a smaller pump line that the Super II (meaning even a 1HP Super II would be larger than what I have and thus cost more to run).

High is the same speed as a single speed pump while low is half the RPM, half the flow rate, 1/4 the power use.
 
Generally you get a manual switch. Leave the switch on low speed nearly all the time, unless you need high speed for priming, vacuuming or backwashing. The only common exceptions are high speed is often needed for pool cleaners run by the main pump and spas/water features.
 

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You can just add a manual switch to select the speeds (like a 3-way house light switch). If you decide to go that route, I would suggest getting a 1HP 2-speed motor and a 1HP impeller ... that will save more money on power than getting a 2HP 2-speed and be cheaper upfront. You will also need a shaft seal.
 
I agree with Jason, unless you have some water feature that needs it, the 2HP pump is overkill, but you should be able to install a 1.5 or 1 HP impeller and motor in that same pump wet end (this is the part that screws onto the motor shaft) and effectively have a smaller pump. As to switching speeds some motors come with a small speed change switch mounted to the end, others you have to use your own remote mount switch. A common household 3 way light switch can generally be used for this application, although if in a wet environment you may need special waterproof switch covers, etc.

Ike

p.s. this all assumes your pump is currently wired for 240V, which would be needed for either a variable speed or 2 speed pump
 
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