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Install ecobee3 with tekmar TN4 hydronic zone heating system

BumblezillaBumblezilla vancouverMember


I currently have a Tekmar hydronic heating system with a wall mounted boiler. The system includes a Tekmar 422 universal reset module, an expansion module and 2 Tekmar 355 Zone managers. They are all working with a variety of TN4 communicating thermostats, but I decided that I liked the feature set of the Ecobee with regards to HomeKit integration, usability and programming.

Has anyone had any experience with installing Ecobee3's with a Tekmar system running the boiler and zones? From what I can tell, the right wires exist (C, R, W) - I would just not connect the TN4 communications wire and leave it loose... If I do that however, will the pumps still move water or do Tekmar systems need to work only with Tekmar thermostats? I feel confident that the zone valve in theory would open, but I worry that if this was the only zone calling for heat that nothing would motivate the water to circulate as I don't completely understand how the 355 works.

Thanks for any help - happy to provide more information


  • kevinmcckevinmcc Macomb, ILMember
    Answer ✓

    You can test this. Turn down all you thermostats.

    Disconnect wire from TN4 terminal. Next jump R and W and see if pump and zone activate.

  • BumblezillaBumblezilla vancouverMember

    Seems to only turn on the zone valve, but doesn't call for heat on the reset module sadly. Looks like I need either more or less tekmar hardware (more meaning something that converts heat demand into TN4 signals) or less (meaning too complex a system) for Ecobee 3

    Thanks anyways though.

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