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Help with an HVAC Event for a Heatpump system.

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  • Help with an HVAC Event for a Heatpump system.

    Hi all,
    We just had a Heatpump system installed in our home and it's set so that the heap pump comes on at 2f difference and the emergency heat strips at a 4f difference.

    Example:
    Current Temp 66f
    We set the temp to 68f, then the Heatpump comes on and warms.

    If we set the temp to 70f or higher, the Heatpump & the Emergency Heatstrips come on.

    So, I'd prefer the heat to raise slowly over time instead of the Heatstrips coming on or if the kids raise the thermostat way high...
    Is there a way to make an Event do this? So if the Heat Setpoint is changed, change thermostat to 2f higher then once at the 2f higher mark, set thermostat to 2f higher again and over and over until it reaches the particular setpoint?

    I've got a Remotec z-wave thermostat. Attached is the PDF Manual.

    Thanks all for the help!

  • #2
    Handling by an event may be a bit tricky. You'd need to create an event that responds to a change to the setpoint and then in response to a change executes a script that calculates the difference between the setpoint and current temperature and re-adjust the setpoint if it is too far from the current temperature. This would require some scripting knowledge and would, effectively, override the user's input at the thermostat to now allow input of more than 2 degree change at a time.

    Better approach -- Multi-stage heat pump thermostats generally allow you to set the stage differential - that's the # of degrees that you have to be away from the setpoint before you go into stage 2 or emergency heat operation. If you can adjust / control that via the Thermostat software rather than HomeSeer, you might be better off. I took a look at the link you indicated and, at least for the Reemotec ZTS-500US, that's controlled by z-wave Parameter #3. It is set to 2 degrees f by default. Set that to 4 for a 4f differential.

    You can also set the upper heat point limit (and lower cool setpoint) to avoid the problem of kids setting it too high / low - that's what I've done on mine.

    Comment


    • #3
      You may want to consider upgrading to a better thermostat. Some will let you lock out the aux (electric heat coils) if the outdoor temperature is above x degrees, where you set x, so you could set it so that there would be no electric heat until the outdoor temperature went below 10 degrees as an example.
      Where I am, it never gets cold enough to need the aux heat except when the unit is defrosting or if it has failed. I moved the white wire from the "W" to the "E" terminal. That way my aux heat only comes on during defrost, or if I switch the thermostat to emergency heat. Unfortunately, it looks like your present thermostat does not have an "E" terminal or emergency heat mode.

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      • #4
        I'm located in southern MO so it does it cold some nights... so changing the white wire to just turn on in emergency mode won't work for me as i'm sure it will get cold enough sometimes the heatpump will not be enough.

        I went ahead and changed the differential so now were at at full 6f in change before the heat strips go on. We usually set it to 65f at night and 68 during the day so technically the lowest the temp would be is 63 at night then turning it onto 68 in the morning would only be a 5f difference so this should be perfect.

        I'd prefer to lockout the thermostat from anyone touching, but have a code or combination to get into in to set it manually. But looking through the manual it does not seem to have that option.

        Thanks all for the help!

        Comment


        • #5
          Good luck. One issue you may encounter with that is that if it is really too cold for a heat pump, then you'll get your heat strips on if you are more than 6 degrees from the setpoint, but you'll never really get to the right temperature as the strips will turn off too soon. More sophisticated thermostats include options whereby once the thermostat triggers stage 2 or triggers the heat strip, it will keep the stage on until it gets to the right temperature. I use Honeywell Prestige IAQ thermostats for that purpose (I think the setting is called something like "Finish with High Heat stage" ) - in my case, they're connected to a geothermal heat pump, but they work just as well with a "traditional" air source heat pump. They aren't Z-wave, but I use the Honeywell Plugin to allow them to be controlled by HomeSeer. The Honeywell aren't that "consumer friendly" to install, so you might also consider the Nest which has more sophisticated control over the multiple stages (allowing the thermostats to take into account outdoor temperature when operating heat pumps, etc.) - plugins are available to then use with HomeSeer.

          Comment


          • #6
            I'm considering this thermostat (Remotec ZTS-500) for an installation in N. California with two-stage gas furnace and single-stage AC. It appears to make a lot of sense with all of the programming in Homeseer. Does anybody care to share experiences? Would the 2F (or 4F or 6F) delta between the setpoint and thermometer trigger my second stage of natural gas heat? Any reason to consider on of the other Z-wave offerings over this model? Does it work reliably from 24VAC with a common wire? Some Amazon reviews indicate it doesn't, but one never knows the competence of the installer.

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