I have the 8320 (model TH8320U/1008) tstat and have some question;
1) The manual states to press the "System" key and then press the middle blank button to access the advanced settings. But there is no system key on the display. Another web site indicated to press and hold the two blank keys next to the middle key, but that does nothing also. Can someone confirm how to access the adv variable settings?
2) What is the difference between the 8320 and the 8321?
3) What about the IAQ differences? Is it significantly better?
Side info: Tstat is connected to a duel fuel XL16i HP with a XV90 gas blower.