I just had a 5 series Waterfurnace split system installed in my house ... Everything seemed great until the outside air temperatures exceeded 85 F. When the temperatures are hot, the system runs continuously on stage 2 and never reaches the set temperature of 78 F- the temperature stays at 80 f The humidity has risen to as high as 70 %. The contractor has checked the coil temperatures when the outside temperature was 82 and said they were better than specification. My old heat pimp cooled the upstairs rather easily. There were slight ducting changes made at the fan unit due to where the fan unit was placed. My contractor does not know why the system is not performing .... He plans to come back out to troubleshoot. The easiest explanation could be a duct leak but are there any other thoughts.?