Programming Strategy For New Variable Speed Pump Motor

[Chuck_Davis]

I'm awaiting delivery on an EcoTech variable speed motor to go with my Hayward SuperPump. While I'm waiting I figured I'd pick the collective brain on the best strategy for programming the motor. I'll lay out my current thinking, but I would greatly appreciate any comments or suggestions.

I found an old thread at http://www.troublefreepool.com/threads/29410-Optimal-flow-rates-for-variable-speed-pumps, but there may be some new experience (or scar tissue) since then.

I have a 15,000 gallon IGP, Liquidator, heat pump (min. 20 GPM, bypassed in winter, long piping run and significant head increase when in-circuit), waterfall water feature and Blue-White flowmeter.

I believe the two starting points for my strategy should be: A) It is better to run the VS motor at the lowest possible speed for as long as is necessary, and B) The Liquidator requires a stable daily pump operating profile of speed and hours.

For winter, with the heat pump bypassed, my current thinking is:

** Open fully the valve to the water feature.
** Set the Liquidator to "medium" flow setting (3).
** Set the pump to run 24 hours a day.
** Find the minimum speed at which the water feature will operate, the pool will circulate and carry debris to the skimmers and at least 15,000 gallons per day will pass through the filter.
** Decrease flow to the water feature if necessary.
** Decrease run hours or increase speed to maintain target FC level. If speed is increased, decrease flow to the water feature.

For summer, with the heat pump in-circuit:

** Open fully the valve to the water feature.
** Set the Liquidator to "medium" flow setting (3).
** Set the pump to run 24 hours a day.
** Find the minimum speed at which the heat pump will operate and maintain the desired temperature, the water feature will operate, the pool will circulate and carry debris to the skimmers and at least 15,000 gallons per day will pass through the filter.
** Decrease flow to the water feature if necessary.
** Decrease run hours or increase speed to maintain target FC level. If speed is increased, decrease flow to the water feature.
** Hours and/or speed will probably have to be tweaked across the course of the (North Carolina) swimming season. Make notes!

I don't know how much I'll be able to tip the balance of this exercise from art towards science, but any assistance in this effort will be appreciated.

 

[JasonLion]

You are generally on the right track, though you don't need to move 15,000 gallons a day, nor should you need anything even remotely close to 24 hour a day run time. The whole one turnover a day thing is an old rule of thumb that doesn't really apply to residential pools.

It is possible to run the pump too slowly. The efficiency peaks at a fairly low speed, but then goes down again at the very lowest speeds. We don't know exactly where that occurs for this particular pump, but on other variable speed pumps it is around 1,000 RPM.

The most important step is finding out what speed everything works reliably at, and then run about 4 to 6 hours a day, or whatever runtime is required to keep the Liquidator happy. Run time can be even shorter than that in the spring/winter.

 

[Chuck_Davis]

Thanks. The 24 hours was just a starting point from which to begin dialing back. Based on your suggestion I'll probably start with 8 hours of run time.

Once I figure out the total number of run-hours needed, I can shift the hours to different part(s) of the day. What is the best time of day to have chlorine being added by the Liquidator?

 

[JasonLion]

There are some extremely minor advantages to adding chlorine during the day. But if you have time of day electrical pricing it is well worth running the pump at night. If neither of those are an issue, then running in a couple of different blocks spread around the clock has some advantages.