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Installed Tekmar 518 and now in floor heating runs non-stop.

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thetrualbertan
thetrualbertan Member Posts: 2
edited April 3 in Thermostats and Controls

Hi all. I replaced my old Tekmar 508's with the newer 518's. Seems the pulse width modulation is causing this thermostat to kick on my in floor heating system almost non-stop (stacking). The hot water heater is cycling on and off. The 508's ran more stable but still stacked, which is funny because I got the 518 as i was hoping it would be even more stable. Unfortunately it's very much not.

The funny thing is it's almost like the 518 can't reach it's setpoint. Even with the system running almost non-stop, the feedback temperature on the display has dropped. I don't see how tho, I'm inputting a major amount of heat into the slab.

Just keeps going and going an going. T-stat was installed this morning.

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 10,754

    i just found this query from last month with no replies. I wonder if there has been some sort of resolution?

    Not quite understanding the problem with "Stacking" temperatures. Can a Terkmar 508 or 518 do a water heater?

    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: 25,326

    Is it wired like one of these diagrams?

    What does the screen display? It tells you what mode the stat is in.

    Screenshot 2025-05-19 at 8.32.19 PM.png Screenshot 2025-05-19 at 8.32.57 PM.png
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream

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