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Which way?

Joe Mattiello
Joe Mattiello Member Posts: 703
To facilitate the wiring, and provide priority with an optional priority protection, you can use 2, Taco ZVC406-EXP switching relays interfaced through the expansion terminals for 10 zone capacity. These boards are easy to install, and have the optional priority protection cards available that will resume heating the home if the indirect water heater calls for more then 60 minutes. Additional post purge, and pump exercise cards are also available. These zone control relays have a quick connect interface terminal to add on controls for outdoor reset, injection mixing, or 2 boiler staging controls. How cool is that!! They even have diagnostic lights to help trouble shoot a problematic system. The priority feature is controlled with a simple on/off toggle switch, so I would suggest operating the system, without the priority turned on, and if you hear any complaints from family members running out of water simply hit the priority switch to on. Can’t make it any easier then that!! For your reference I attached catalog data, and the famous Taco zone control wiring guide.
Joe Mattiello
N. E. Regional Manger, Commercial Products
Taco Comfort Solutions


  • adambuild
    adambuild Member Posts: 413
    Indirect control.................

    Hi Wallies,

    Installing new indirect replacement for leaking one. Old one was fed by zone valve and prioritized with Argo AZV246P, one of ten zones. We are feeding new indirect with circ and need to control with priority. What's the best way?

    Thanks in advance, Adam
  • ALH_4
    ALH_4 Member Posts: 1,790

    Assuming there is no mixing or reset control, the Tekmar 260 would be my choice.
  • ScottMP
    ScottMP Member Posts: 5,884
    with that many zones

    I would assume a good size home. Do you really want to prioritse it ? Thats alot of house to go cold if it gets stuck in priority.


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  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
    Curious why change

    The P in your relay stood for priority which is an option provided you wired things correctly. If the old configuration worked ok before why would you want to go though a major plumbin and control change?

    FYI, I am not implying you shouldn't. The Tekmar 260 would be an asset to your system.
  • Valid concern

    But have you ever seen a control get stuck in priority ? I'm assuming you mean the control goes bad , Scott ?

    We used Argo in the past and it is one sturdy control - made more sturdy with the sealed contactors . Which don't mean squat if it got hit with water or an electric surge or the indirect aquastat goes funky ..... or when there really is a long demand for hot water on a cold day . Still , I gotta think the control going bad is a rarity ?

    Easiest way to keep priority is to find a relay that will pull in with low voltage and connect it to the zone valve terminals for the priority zone . Then run line voltage through the dry contacts of that relay to power the circ . Sorry , I don't know brand names or models numbers for such a beast .

    Another option is an Argo or Taco single zone relay with separate NO-NC contacts . The T-T terminals of this relay would work the priority zone . To prioritize that zone you would power the Argo multizone relay through the Common and NC contact of the single relay . To be on the safe side you could wire a switch between COM and NC to bypass the priority if needed .
  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
    automatic override

    I believe that control, even though it is an older version has an override so that if the DWH demand goes longer than some preset time (I think around 40 minutes) it automatically disables the priority function.
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