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Trane TZEMT400AB32MAA too sensitive / short cycles

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    Trane TZEMT400AB32MAA too sensitive / short cycles

    Hello All,

    I installed the thermostat last winter and had no issue during the heating season. I have a two story house with baseboard HW oil heat with a air handler and duct work for central air that was added later.

    The thermostat is located at the top of the steps in the hallway. The single a/c return air grille is located in the hallway as well.

    Now that we are in the A/C season I have noticed that the thermostat has been running for the 9 minutes of the minimum on time and then it shuts off for the minimum 9 minutes of off time and then repeats. It is holding the 76 degree set point but it is not dehumidifying as well as I would like.

    I reinstalled my old thermostat and it is running for 30 to 40 minutes cooling down to 75 degrees and then shuts down until the house warms back up again. The system is also dehumidifying the house as it should.

    I have tried throttling the upstairs vents and have set the blower fan on it's slowest speed.

    The documentation does not have any info on changing the temperature sensitivity or any other settings. Has anyone else seen this issue or have any suggestions. My thoughts are that the thermostat is very sensitive on the temperature side and the return air flowing by the thermostat is amplifying the issue.

    #2
    I had this problem with an old X10 stat and finally took it out. The only way I know around this issue is to use events to capture the setpoint. When the unit starts automatically set the setpoint one setting lower. Then when it stops set it one setting higher. I would have thought this stat had the ability to change the internal trigger to more than one degree but as far as I know it doesn't. The minimum run time must be the way the manufacture attempted to accomplish this.
    -Rupp
    sigpic

    Comment


      #3
      I have this same stat and have been noticing the same behavior. I found the manual online and looked into the installer settings and sure enough, the minimum on time is listed as 1-9 minutes and the minimum off time is listed as 5-9 minutes. I have not tried manually changing those numbers to about 30 minutes, but I am thinking it will probably not take the input if it is out of that range.

      I have been using the internal schedulers on the stats to this point, but I am thinking of changing over to using BLStat, or events to control the unit (I was testing the stats and making sure everything was working correctly before I put them totally under HS control).

      Rupp, what do you mean by using events? Are you saying something along the lines of at 10 PM put my setpoint to 76, then once the system reports being at 76 bump the setpoint to 77, when the temp is reported at being 77 bump the setpoint back to 76 and so on? I only really seem to have this issue at night, or maybe that is just when I notice it.

      Comment


        #4
        Originally posted by chewie View Post
        I have this same stat and have been noticing the same behavior. I found the manual online and looked into the installer settings and sure enough, the minimum on time is listed as 1-9 minutes and the minimum off time is listed as 5-9 minutes. I have not tried manually changing those numbers to about 30 minutes, but I am thinking it will probably not take the input if it is out of that range.

        I have been using the internal schedulers on the stats to this point, but I am thinking of changing over to using BLStat, or events to control the unit (I was testing the stats and making sure everything was working correctly before I put them totally under HS control).

        Rupp, what do you mean by using events? Are you saying something along the lines of at 10 PM put my setpoint to 76, then once the system reports being at 76 bump the setpoint to 77, when the temp is reported at being 77 bump the setpoint back to 76 and so on? I only really seem to have this issue at night, or maybe that is just when I notice it.
        With my old X10 stat it would notify of a temp change. When the temp would drop below the setpoint I would run an event to set the setpoint one degree lower that the current setpoint. Once it reached this setpoint I would set it to one degree above the in initial setpoint. This way it was mimicking a 2 degree offset. This quickly became unmanageable with the X10 stats but with the right coding may work on these newer stats if they report their status. I would also check out the HAI stats as I believe they offer the offsets as an adjustable parameter.
        -Rupp
        sigpic

        Comment


          #5
          I gotcha, so essentially something like this:

          6 AM change setpoint to 81
          When temp reports 82 change setpoint to 79
          When temp reports 79 change setpoint to 81
          8 PM change setpoint to 77
          When temp reports 79 change setpoint to 77
          When temp reports 77 change setpoint to 79
          10 PM change setpoint to 75
          When temp reports 77 change setpoint to 75
          When temp reports 75 change setpoint to 77

          The main setpoint events can be done by time, the reactive setpoint events can be done using Conditional Events based on the time intervals surrounding the main setpoint events.

          This should achieve around what I am looking for, which is 80 during the day, cooling to 78 in the evening and 76 for sleeping, while also solving the issue of the AC kicking on and off constantly.

          That sound reasonable?

          Comment


            #6
            I am also seeing short cycles during cooling. Today is the first day I am running the air conditioning. After reaching the set point, my unit was cycling every 3 minutes. So I changed The minimum ON time to 9 minutes (maximum allowed) and the minimum OFF time to 9 minutes (maximum allowed). It is working better now but I would prefer it to run for 15-20 minutes.

            I also found a setting for the "delta" between the ON/OFF set points. The default is 1 degree but it can be adjusted from 1 to 8 degrees. I am going to try 2 degrees.

            Steve Q
            HomeSeer Version: HS3 Pro Edition 3.0.0.368, Operating System: Microsoft Windows 10 - Home, Number of Devices: 373, Number of Events: 666, Enabled Plug-Ins
            2.0.83.0: BLRF, 2.0.10.0: BLUSBUIRT, 3.0.0.75: HSTouch Server, 3.0.0.58: mcsXap, 3.0.0.11: NetCAM, 3.0.0.36: X10, 3.0.1.25: Z-Wave,Alexa,HomeKit

            Comment


              #7
              Yeah, I tried to implement what I described above, but none of the conditional events I mentioned seem to be triggering. I am trying to figure out why. Currently I am using BLStat events for the conditionals.

              Comment


                #8
                Originally posted by Steve Q View Post
                I am also seeing short cycles during cooling. Today is the first day I am running the air conditioning. After reaching the set point, my unit was cycling every 3 minutes. So I changed The minimum ON time to 9 minutes (maximum allowed) and the minimum OFF time to 9 minutes (maximum allowed). It is working better now but I would prefer it to run for 15-20 minutes.

                I also found a setting for the "delta" between the ON/OFF set points. The default is 1 degree but it can be adjusted from 1 to 8 degrees. I am going to try 2 degrees.

                Steve Q
                I also changed the on setpoint delta for the cooling to 2 degrees. It seems to be working good for me.

                Comment


                  #9
                  Originally posted by Steve Q View Post
                  I am also seeing short cycles during cooling. Today is the first day I am running the air conditioning. After reaching the set point, my unit was cycling every 3 minutes. So I changed The minimum ON time to 9 minutes (maximum allowed) and the minimum OFF time to 9 minutes (maximum allowed). It is working better now but I would prefer it to run for 15-20 minutes.

                  I also found a setting for the "delta" between the ON/OFF set points. The default is 1 degree but it can be adjusted from 1 to 8 degrees. I am going to try 2 degrees.

                  Steve Q
                  Steve,
                  Where is this set as this is exactly what needs to be changed and what the earlier logic was attempting to replicate.
                  -Rupp
                  sigpic

                  Comment


                    #10
                    I think I found the setting. In this stat you hit Menu and then hold down both of the middle buttons until it drops you into the Installer Settings. What I changed in mine (Just changed it so we will see how well it works over the next couple of days) were the Heating Delta Stage 1 On and Cooling Delta Stage 1 On settings. I changed these to 2 so theoretically this should let the temp get 2 degrees above the setpoint, then the unit should kick on and cool to the setpoint causing it to run less frequently but for longer runs during its cooling cycle. Again, theoretically this should make my units more efficient both in terms of cooling and dehumidifying the house as well as electrical usage since it takes more power to start up the unit over and over again than it does to run them once they are started.

                    Comment


                      #11
                      Originally posted by chewie View Post
                      I think I found the setting. In this stat you hit Menu and then hold down both of the middle buttons until it drops you into the Installer Settings. What I changed in mine (Just changed it so we will see how well it works over the next couple of days) were the Heating Delta Stage 1 On and Cooling Delta Stage 1 On settings. I changed these to 2 so theoretically this should let the temp get 2 degrees above the setpoint, then the unit should kick on and cool to the setpoint causing it to run less frequently but for longer runs during its cooling cycle. Again, theoretically this should make my units more efficient both in terms of cooling and dehumidifying the house as well as electrical usage since it takes more power to start up the unit over and over again than it does to run them once they are started.
                      Yes, the setting is in the "installer settings" in the "system settings" (see attached). I changed only the "Cooling delta stage 1 ON" from 1 to 2 degrees. I did not change the OFF delta (default is 0) because it is not clear to me what this does?

                      My system is now running for a minimum of 12 minutes but typically 15 to 22 minutes. This is where I think it should be.

                      Now I need to add some setpoint changes based on outside temperature/humidity.

                      Steve Q
                      Attached Files
                      HomeSeer Version: HS3 Pro Edition 3.0.0.368, Operating System: Microsoft Windows 10 - Home, Number of Devices: 373, Number of Events: 666, Enabled Plug-Ins
                      2.0.83.0: BLRF, 2.0.10.0: BLUSBUIRT, 3.0.0.75: HSTouch Server, 3.0.0.58: mcsXap, 3.0.0.11: NetCAM, 3.0.0.36: X10, 3.0.1.25: Z-Wave,Alexa,HomeKit

                      Comment


                        #12
                        Thanks Steve.
                        -Rupp
                        sigpic

                        Comment


                          #13
                          So after changing those settings my stats appeared to run for longer intervals and then stay off for a good while before firing up again.

                          Thanks Steve!

                          Comment


                            #14
                            Well I reinstalled the thermostat today and changed my 1st stage on delta cool 2 to as you guys have and will try it out.

                            Their explanation for the 1st stage delta off seems backwards. I almost want to put a -1 value in there to achieve to following.

                            Set point at 76 degrees, temp will rise to 78 degrees and system will turn on and cool down to 75 degrees and turn off.

                            The documentation suggests that if you put a 1 in the delta cool off you get the following.

                            Turns on at 78 degrees and turns off at 77 degrees.

                            Comment


                              #15
                              Let us know if that works for you, if so then I will probably dothe same. I like that logic.

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