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2441TH Three Wire Thermostat Installation?

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    2441TH Three Wire Thermostat Installation?

    I'm trying to install 2441TH thermostat at my house, but found the cable has only 3 wires (R, W, G; the old thermostat only uses two wires R+W). The wall that installs the old thermostat is close to stairs, and the stud structure is complex, so I couldn't find a way to replace the old cable with new 5-wire cable.

    After searching on web, I came up with method to connect 2441TH with 3 wires, but want to confirm if that is correct.

    2441TH side, wire, furnace side
    24R --------- R ---------- R
    W --------- W ---------- W
    24COM --------- G ---------- C

    Also if I like to control the fan separately, can I use the “Add-a-Wire” adapter to split W and G wire?

    Thanks for your input.

    #2
    If you are controlling heat only, and it appears that you are, then your wiring method is correct. Nothing else is needed.

    You can use the Add-a-Wire kit which will enable you to control the fan separately, that is, on only when heating or on all the time if your panel has a functional G terminal.
    Message from Forum Admin: stusviews passed away in April 2018. Stu was a huge fan of Insteon and a huge presence on both the Smarthome and Insteon forums, helping thousands of us along the way (he had nearly 20,000 posts to his name). We thank him for his contributions, dedication, and passion for making the Smart Home a reality. He will truly be missed.
    Saving energy is not always free. Be a world saver.

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      #3
      stusviews Thank you for confirming the solution.

      Comment


        #4
        stusview, I guess that I need more help on the thermostat.

        The thermostat lost power frequently with the three-wire configuration for heat only. Based on my observation, each time after the furnace started heating for a few minutes, the thermostat lost power, the display on the thermostat disappeared, and it won't respond to any key. The furnace continues to run at this time, not sure how long does it take to stop. But after a while, the thermostat got power again, and restarted. Sometimes, it may took too long to receive power, and the thermostat lost all settings.

        Is it possible caused that the 24v ac transmitter in furnace does not have enough capacity? What is the best solution to solve this issue? changing to a higher capacity 24v ac transmitter? or adding a separate one for the thermostat?

        What is the power 2441TH expect? 24v AC or 24v DC? And what's the minimum current requirement?

        Thanks.

        Comment


          #5
          The thermostat uses very little power. If it did, in fact, lose power completely then the furnace would shut off. More likely, the C wire is not secure. It's also possible that the thermostat is defective.

          In particular, the thermostat needs power to light the display and keep the schedule. The schedule is in non-volatile memory so it's not lost, but the clock needs constant power. Did you set the time? Does the clock keep time when the display returns?
          Message from Forum Admin: stusviews passed away in April 2018. Stu was a huge fan of Insteon and a huge presence on both the Smarthome and Insteon forums, helping thousands of us along the way (he had nearly 20,000 posts to his name). We thank him for his contributions, dedication, and passion for making the Smart Home a reality. He will truly be missed.
          Saving energy is not always free. Be a world saver.

          Comment


            #6
            The time and settings are persisted at most of time because the power will be recovered in a short time. But I saw the setting got reset a few times, the symptom was that the mode was set to Heat, but changed to Off automatically.

            It could the control board issue on the furnace, because I measure the voltage on the thermostat side, and it was 0 when the thermostat was no display.

            I purchased a 24v AC transformer and a 24v relay, and connected them as the diagram shown at http://www.smarthome.com/venstar-the...-only-kit.html, and the system runs fine till now.

            Thanks again for your help.

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              #7
              I realize this is an old post, but I have the same identical problem. Although I am waiting for a 24VAC circuit tester from Amazon, I see here that Shihua found zero voltage during screen loss, and I suspect I will find the same. The lack of the G wire is, I believe, due to the fact that this furnace has a limit switch to turn the fan on and off based on direct measurement of the furnace temp. I think maybe when the limit switch kicks in, it must be turning of or interfering with the 24VAC to the gas valve and thereby to the thermostat? I will purchase a separate power source and test. Thank you for this post.

              Comment


                #8
                The 24VAC should be between the 24COM and 24R on the 2441TH terminals. To power the display.

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