If you have a Geostar Sycamore or Aston water-to-air heat pump and a Geostar thermostat model TPCM32U04A or TPCC32U01, your system has the capability to control humidity (somewhat) independently of temperature.

To activate that capability on the TPCM32U04A: From the main menu, select “RH” or “REL. HUM”. Then choose “DEHUMIDIFY” or “BOTH” (if your system has a humidifier also).

From the TPCC32U01: From the main menu, press the “MENU” button, then “HUMIDITY”.

Generally, a setting of 50% relative humidity during the summer will be satisfactory to be comfortable; much lower than that may tax the system, depending on outside weather conditions, and will definitely add to your electric bill.

When in cooling mode, if the thermostat temperature is satisfied but relative humidity is above the setting that you programmed, your system will reduce fan speed while maintaining compressor speed to remove proportionally more moisture from the air… so long as the room temperature doesn’t fall more than a few degrees below the thermostat setting. Given the room temperature constraint, it could initially take days to bring the humidity down to target… provided that additional moisture isn’t introduced (e.g. by opening windows on a warm and/or humid day) in the interim. To speed up the dehumidification process, lower the thermostat temperature setting to remove the constraint.