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Tekmar 351

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I have a Tekmar 351 thermostat that needs to be replaced. I would love it for someone to explain how it really works in layman's terms, and what you recommend for a replacement.

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  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
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    Signgirl said:

    I have a Tekmar 351 thermostat that needs to be replaced. I would love it for someone to explain how it really works in layman's terms, and what you recommend for a replacement.

    Tekmar never had a thermostat 351. They had an injection mixing control, discontinued. So it’s hard to give advice until I (we) know which component you are referring.
    Take/post some pics.

    There was an error rendering this rich post.

    Zman
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,050
    edited November 2020
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    The 351 control used an RTU-051 as a thermostat. It is a 2 wire digital devise that communicates with the 351. Not an analog switch that opens and closes.

    If you want to change the thermostats you will need to change the entire controller with something that will operate the injection pump.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • hot_rod
    hot_rod Member Posts: 22,251
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    It was a mixing control, had the ability to take an input from a remote sensor as @EdTheHeaterMan mentioned. It was a great control, showed up at a few of the radiant manufacturers offerings.
    Probably early to mid 1990's. Might be time to upgrade.
    tekmar keeps data on obsolete controls at their site.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream