Trane Tcont900 Humidity Control

[4Kids]

I am a newbie with a recently installed XL20i/XC80 communicating system with the Tcont900 TStat. TStat parameter 0380 is currently setup for ITHC control with parameter 0383 set for 2°F undercooling. The Temp setpoint is set at 76°F/50% humudity. The unit has saved me lots of $$ and operated flawlessly during the hotter days by mantaining temp and humidity in 50-52% range. With the cooler days we have been having in Texas, I notice that the humidity has crept up and the unit seems to maintain the 76°F temp but the acutal humidity seems to be maintained at 55%. I would have expected the unit to subcool to a 74°F to try and bring the humidity down closer to the 50% setpoint value.

I have been monitoring the system and it seems that as soons as the humidity creeps up to about 56-57%, the unit will call for cooling but it will not subcool past 76°F and will turn off as soon as the humidty approachs 54-55%. It almost seems like there is a 5% deadband on the humidity setpoint and it will turn the unit off as soon as it gets within that deadband.

I have tried changing parameter 0380 to trane droop but has made no difference in operation. I have also tried to increase subcooling parameter 0383 to 3°F with ITHC operation.

I wonder why the unit won't subcool more to try and bring the humidity down closer to the 50% setpoint?

[beenthere]

Set the humidity level to 45%. The deadband is what is doing it.

[4Kids]

Beenthere,

Thanks for the quick rely. I'll try that this weekend. It really does not make sense that you would need to tweak the humidity setpoint for weather changes but I do agree that it might be my only option since there are no available parameters to tighten the humidity deadband. Needless to say, the ITHC algorithm appears to need a little tweaking in the area of humidity control.