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Has anyone tried to control a normal circulator with a triac board?

BigRobBigRob Member Posts: 215
I'm looking at triac variable speed boards to vary the speed of a normal, fixed speed circulator. After some research I learned that at least some of the Grundfos variable speed hydronic circulators are controlled with triac based AC chopping boards. I noticed Taco offers most of their pumps with a variable speed option, so I'm thinking they just pop in a triac controller and call it a day. Does anyone have any more information?


  • SWEISWEI Member Posts: 7,356
    Wet-rotor circulators

    with PSC motors respond well to standard TRIAC control down to about 60% voltage.  Below that, you need PWM logic a la Taco or Resol.
  • hot rodhot rod Member Posts: 7,014
    wave choppers

    most of the smaller, basic solar controllers have triac relays on board.

    The Resol based controls allow 30- 100% speed control and a 1 amp load. When we need to switch larger loads add one of these Omron, or other brand, solid state relays to the solar control (120V) output, now you can switch up to 25A. But you need to mount them on a good heat sink, they shed a lot of heat, at high current draws. We connected a 5hp shop vac to this relay and it got too hot to hold very quickly :)

    The larger, more advanced Resol based solar controls have a PWM output as well as triac on R1- R4. Some of the Euro solar pumps from Grundfos have the plug that matches that mini molex included

    Also the connections for the Grundfos vortex flow and pressure sensors, are included on some models.

    44F and rain here today, not much solar potential.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • BigRobBigRob Member Posts: 215
    When you say..

    PWM logic, are you referring to a pump with a PWM input pin for a control signal, or are you talking about the PWM method of a variable frequency drive?
  • BigRobBigRob Member Posts: 215
    Thanks for..

    ..the pictures. What I'd like to do is add variable speed control to my boiler pump for less money than a new variable speed pump. I would also like to find a deltaT controller for my heating system pump, with or without speed control. If without, I would need a 0-10v output.

    The solar controllers look neat. For heating I would need to turn off the tmax and min. Have you ever used the solar controllers for a heating deltaT application?
  • hot rodhot rod Member Posts: 7,014

    I have 4 different VS ∆T functions on my shop system P1 P2 P3 and P4. Wood boiler to ThermoCon is one, I did add a thermostatic mixing valve pump block, return valve since this drawing. i have made some other piping changes since this drawing, but same control functions. The Phoenix is now dedicated to the radiant, either wood, solar, or LP powers the radiant.

    DHW is via a plate HX on the side of the Phoenix. A flow switch triggers the HX pump when a faucet flows.

    next is the ThermoCon to the solar tank VS ∆T Both run off one I-solar plus control, which has two VS relay outputs..

    Across the shop I have a DB solar, and solar to Phoenix as a ∆T functions running off the I-solar MX LTE. After I pull some additional wires the MX LTE has enough functions to run everything from one control.

    The wave choppers are not as friendly to the circ motors as a true PWM speed control. But in 8 years I have yet to see a motor failure. The motors do pulse at low speeds and we have had a few cause vibration in the piping to the solar if the pipes were not supported well.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • BigRobBigRob Member Posts: 215
    Cool system

    I will read the manuals. What would be optimal for me is a triac controller with two 0-10v inputs, one each for one triac, then a deltaT controller controlling a 2A third triac or a 0-10v output.

    Do you know if the Taco and Grundfos variable speed pumps are using triac speed control? I assume so based on some searches.

    Also, I saw the legiomix system and love it. Perfect for our building. Let me know if you need US beta testers. I'll give you great data and feedback. Will it be available in the US? Are there other systems out there? After my thermostatic valve disaster I want to nuke the problem.
  • BigRobBigRob Member Posts: 215
    Forgot to ask..

    What kind of flow switch did you use? I'm looking for one, but I don't want a paddle type.
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