Varible Speed Controller For Wet Rotar Circulating Pump

Sorry...

That pump has an induction motor.  Therefore, the only way to change the speed is to change the frequency of the current coming into it.  I suspect there are variable frequency controllers available.  I also suspect that they aren't inexpensive...

TRIAC speed control

Can work on single phase induction motors, as long as you understand the limitations.  It's not particularly efficient -- you don't save all that much energy turning them down, unlike VFD with a 3ø motor -- but it does work.  What we're talking about is in effect a smart version of a TRIAC lamp dimmer.  You have to provide full power for a couple of seconds in order to get the motor to start, then ramp down do the desired speed.  Turndown is limited in most applications, but for the special case of a circulator pump you can pulse power to the motor below that cutout, effecting near-complete control over speed.  Tekmar, Heat-Timer, Caleffi, Taco, and others do this in some of their controls.



I have a board that will do the basic "smart dimmer" function but does not handle the low speed pulsed operation.  It's not a packaged product, but it can be integrated with most any control system.

It's ugly

if you put a 'scope on it.  Efficiency drops along with speed, so of course more of the input energy turns into heat.  Given that typical single-phase fractional horsepower motors start out somewhere in the 50-60% range at full speed, it's not hard to see why ECMs made their first appearance in small circulators.

swei

when do u use those controlers? and y? just tryin to learn