Would anyone out there happen to have experience with a retro-fit VFD controller for a pool pump system? I'm interested in the complexity of the the retro-fit as well as the measured savings.
Eric, I'm not familiar with pool pumps in particular but in general VFDs provide savings for situations where there are variable loads. I thought pool pumps were just on/off applications.
A typical scenario is a hydronic system with multiple zones and a single pump. The load changes as zone valves open and close. A VFD can really shine in that situation.
If your flow is fairly constant just use the highest efficiency motor available.
Forgive me as it has been awhile as I hardly see any pools around here, but one must remember that not all VFD's work with all motors so this is one major consideration.
Retrofitting is dependent on location & type - a variable speed pump with an integrated one is pretty easy & will probably save you money compared to one from just a few years ago. A wired one mounted outside depends on space & what it takes to mount, etc... A wired one located in the house is dependent on how hard it is to fish the wires. A wireless one is generally pretty easy though some might have issues with interference, getting signal though some buildings & generally cost a lot more.
Personally I would look for an integrated one that can be programmed & will shutoff if it starts to require more than X power for so many GPM (indicating blockage, needing a back-flush (or automatically performs one), etc...)
Don't forget to look into time of use plans with any system where you can run them cheaper at night which also helps cut down on evaporation.
As for savings - you would have to crunch the numbers & make sure you are running it when required instead of going overboard like many do
Now just in case you are going commercial - a wired one that can handle multiple pumps located in a pump house is generally the way to go (along with a notification system makes life easier)
Eric, I have been looking also. From what I've seen I think the savings for me will be significant.
The things you need to do a comparison:
1. The system head and flows, pipe diameters, etc...
2. The current motor manufacture and pump manuacturer, the pressure/flow curves, rpm, etc... (motors can be paired with different pump heads).
3. Current energy use if you have it.
I'd contact three or four of the pump manufacturers that specialize in VFD's for pools and see if they can give you an engineering workup/estimate.
My guess is that they have seen lots of requests - and they may have suggestions for other components that should be upgrade or replaced at the same time (like filtering system).
Replacing my spa pump motors is on my 2014 summer list of activities... so I am interested in how your retrofit works.