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Run a C-Wire to #2 on a Taco Valve? Other location?

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  • hot_rod
    hot_rod Member Posts: 22,158
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    No chattering relays or flickering lights?, you should be good.

    If you use a Nest, it may only present in the battery recharge mode. Some of the experiences I heard of through a wholesaler, happened 6 months after the install. It shower as flickering lights on a system wired with a relay box.

    Some of the newer relay boxes use electronic or optical relays, not sure how they would respond to low voltage conditions, dim, flickering indicator lights generally are a tell tale.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • nickfie
    nickfie Member Posts: 1
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    Just got my Ecobee working with Taco zone control valves. First, how I did it. Second, Ecobee support's suggestion.

    Fortunately, original thermostat wire included 3rd conductor, unused in original installation. A contractor built the house in early '70s for his parents, everything was done correctly and well with good quality material.

    The installation includes 4 Taco valves and two transformers, both transformers' Common leads are connected together in the same wire nut.

    This is a summer home, we only want one Ecobee to ensure temperature stays above 45 in winter, and to report when there is activity in the house.

    How I Connected

    At furnace, connected thermostat lead's unused 3rd conductor (Green) to same point as #2 on Taco valves (Common).

    At Ecobee, connected:
    A. Transformer "Hot" to Ecobee Rh. Half of Ecobee's power connection. (White in my setup)

    B. Freshly-connected "Common" to Ecobee C. Second half of Ecobee's power connection. (Green in my setup)

    C. Taco zone control "1" to Ecobee W1. (Red in my setup)

    This works. Boiler does not kick on until several minutes after Ecobee or other thermostat calls for heat. Ecobee still has sufficient power while triggering valve.

    Ecobee's Recommendation

    Ecobee suggested there could be insufficient power for Ecobee if it uses same transformer to power itself and actuate the Taco valve. They offered two solutions:

    1. Install a dedicated transformer to power Ecobee. Connect new transformer's leads to Ecobee terminals Rc, since we don't have air conditioning, and C. Connect original thermostat wires to Rh (transformer hot) and W1 (Taco control). Figure out how to make living room Ecobee presentable.

    2. Use their separately powered converter devices. Even more difficult to make it look pretty.

    Hope this helps.

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