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  1. #1
    Join Date
    Jun 2018
    Central Florida
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    Balancing temperature and dehumidification

    I recently had a new Bryant system installed which has a dehumidification option. I also have an ecobee4 installed. I live in Central Florida and it's obviously hot and humid during the day.

    Unfortunately, the ecobee does not allow me to change humidity setpoints with in the schedule. I have my home, away, sleep, etc.. temperature setpoints all set depending on the time of day, but the humidification setting cannot change with the scheduling.

    My question is, would I be better off with comfort and efficiency if I chose a higher temperature setpoint with a lower humidity setpoint. Ant example would be:

    Option 1: when home, cooling temp set to 73 degrees with humidity set to 56, with a one degree temperature swing (This I presume allows the unit to run in dehumidification mode even if temp has been reached, assuming humidity is higher than setpoint).

    Option 2: when home, cooling set to 76 degrees with humidity set to 46, with a three degree swing.

    Has anyone tried anything similar to the two options that I stated? was their any benefit or disadvantage to doing one or the other?

  2. #2
    Join Date
    Aug 2003
    Fort Worth, TX
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    Most residential thermostats with a "dehumidification" option, merely overcool the house to increase run time of the system in order to dehumidify. This is because almost no residential system installed uses a form of reheating the supply air after it has been cooled and dehumidified. The result can be a house that feels dry enough, but a bit on the cool side. And, since it is very uncommon for a residential system to have supply air reheat, thermostat makers who market humidity control features resort to either overcooling, slowing the indoor blower down, or both.

    An option outside of a reheat strategy is a whole house dehumidifier that brings in outdoor air to replace stale air in the house. In Florida I wouldn't think twice about having one. Install it, commission it correctly, done. The a/c is then more of a temperature controller vs. a dual role of cooling and dehumidifying. And if the dehumidifier is set up to keep the house slightly pressurized against outdoor air, this reduces humid air seeping into the house through the walls, ceilings, etc. and also pushes drier air into these same voids, reducing mold risk in building cavities.
    Psychrometrics: the very foundation of HVAC. A comfort troubleshooter's best friend.

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