Also cross-posted @ /r/hvac and /r/hvacadviceI am a bit concerned with the poor humidity control of this fancy-schmancy 2-stage unit and have a few questions, but first the details on the system.I have a 2017 Carrier 4-ton unit installed in Central Florida. Condenser: Comfortmaker SoftSound Deluxe 16 CCH648GKA200 2-stage communicating unitAir Handler/Evap: FVM4XB4800 variable speed, TXV.Thermostat: Honeywell Prestige HD 2.0System was also installed with a new copper run.Old system: Carrier 10 seer; 4-ton; R-22; VS air handler w/ dehum; DH occurred with fan ramping down to low speed (about 975CFM) and set to overcool by 1 degree. unit was 18 years old Thermostat: Honeywell Prestige HD 2.0The old system was functioning perfectly with the exception of a slow leak in the evaporator. With small kids and the increased cost of 22, I decided to change it out before the 95 degree days came back this summer.With my old system, when fully charged, it would easily cool the house and dehumidify to around 37%-40%. Quite impressive considering the outdoor temperature was typically between 88-95 degrees with 75%+ RH.The delta across the coil had a 30-33 degree drop with the output temperature at the air handler exit to the duct a consistent 40 degrees when operating on DH. Indoor temp and RH were always set at 75 and RH at 40%. Needless to say it was VERY comfortable.With my new 2-stage unit I have been having a hell of a time controlling the indoor humidity. RH inside is typically around 50%-70% @ 75deg with outside RH at 75% and temps at 88-95.I have verified the following: Subcooling is set to factory spec @ 12 degrees. Coil temp has a design of 50 degrees. Output temp at the evaporator is around 52 degrees Input temp 12" in front of the evaporator is 75 degrees. When a call for DH occurs, system goes to stage 1 (low) and the air handler also ramps way down. Output temp drops to 48 degrees 12" in front of the evaporator.I have a few questions that I would like verified before I call the folks back out so I can ensure that I'm getting a straight answer:Can the subcooling be dropped lower than 12 degrees to achieve a lower evaporator temperature, resulting in improved dehumidification? With a 2 stage unit, when a call for DH is made, is the outdoor unit supposed to cycle to stage 1 (low) and remain there? Keep in mind, with the 2-stage unit, the system runs a LOT but 80% of the time in low, resulting in a power bill nearly $125 less per month than my old unit. Can the subcooling be adjusted to drop the evaporator coil? ie: Spec subcooling is 12 degrees, can I go below that to drop the coil temp? My only complaint is the poor humidity control.Thank you all for any guidance :-) via /r/DIY http://ift.tt/2gEvi1v
