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Tekmar 654 setting

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MichaelT
MichaelT Member Posts: 37
in Radiant Heating

I have a Tekmar 654 controller for my snow melt system. It is connected to my Navien nhb150H boiler. I have the 654 programmed so that my idling temp is 60 degrees. But when I go to the view menu it shows slab target is 70 degrees. Slab sensor is showing 47 degrees. But it is deep in the slab, the actual top part of the concrete slab is only 30 degrees.

(I set these temperatures higher because my slab was not heating to were it needed to be)

It also does not seem to be turning on the system as it should be.

When I walk away from the system for 20 minutes it seems to shut down. The boiler will ramp up and shows a warmer temp over 100 degrees on my Navien boiler. But then after a short amount of time it shuts down. Why would it be doing this? What am I missing?

Comments

  • GGross
    GGross Member Posts: 1,733

    so you are using an embedded slab sensor only and not the puck sensor that detects snow and ice? when you say the sensor is deep, how deep? and how deep is the tubing? how deep is the total slab? tubing size/spacing/length? How do you have the control wired to the boiler? the shutting down is a separate but maybe related issue, have you checked that the call is ending from the 654, or is the boiler shutting itself down on a safety?

    which of these applications did you base your wiring and install on?

    https://www.watts.com/dfsmedia/0533dbba17714b1ab581ab07a4cbb521/81799-source/638820706650000000/654-a-01.pdf

  • MichaelT
    MichaelT Member Posts: 37
    https://forum.heatinghelp.com/discussion/comment/1874144#Comment_1874144

    yes I’m only use an embedded slab sensor. The slab sensor is at the bottom of a 6 instead slab. The tubing is also the same depth. Towards bottom of a 6 inch slab


    I had Tekmar walk me through this. It is single zone just like the page 3 on that link

  • GGross
    GGross Member Posts: 1,733
    edited November 26

    I don't think that sensor will ever give you what you want, not trying to beat you up about it so maybe we focus on the other issue and some folks can chime in regarding what is shutting the boiler down before it reaches setpoint. any error codes? does the boiler have delta T protection active? flow switch safety shutting it down? tekmar call for heat ending early for some reason? Are you sure you have an isolation relay between the 654 and the TT on the boiler so you have a dry contact heat demand and not sending voltage to the boilers dry contact terminals? I think you need to observe the unit shutting down so you can determine exactly what is happening there.

    once the boiler will run with a heat demand all the way through consider adding an aerial sensor

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