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Honeywell T8775 non-programmable thermostat and Taco Viridian circulators?

I'm trying to install a Honeywell T8775 heat-only non-programmable thermostat. I believe I need to use the included resistor because we have 2 different zones with Taco controllers, but they aren't the typical zone valves that Honeywell describes in their install manual. We have 2 Taco Viridian Circulators (#VR1816-HY1-FC2A00) connected to a zone relay. I'm not exactly sure where to place this resistor.

Here are a few photos of the equipment:


  • hot_rod
    hot_rod Member Posts: 21,862
    I think the resistors are to shed away stray voltage when power stealing thermostats are used with just two wires?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • newagedawn
    newagedawn Member Posts: 586
    the resistors are for zone valves with powered t stats, dont need the resistor with that zone panel, just change the t stat
    "The bitter taste of a poor install lasts far longer than the JOY of the lowest price"