I've been trying to educate myself on all this and appreciate all the knowledge that abounds in these forums.
I just had the subject systems installed along w/new ductwork. After the installation, I had an independent energy auditor come out to test the system and there are problems that quite frankly shocked me. I had purchased this gear from a well known and well-respected local installer. BBB, in business for a long time etc. The auditors could not get my cooling system to ramp up to the higher speed. They tried various things, including letting it run for an hour set at 60 degrees. (I live in Atlanta and it's been in the 90s). Also, on the t-stat, while I don't have a humidifier, it seems that I should be able to set a desired humidity-level in the summertime but the t-stat will only 'display' the humidity - it does not allow me to set a desired humidity level.
The auditor said they WERE able to get the air flow to ramp up while the t-stat was in HEAT mode.
I want to be able to talk intelligently to the installers when they come back out. Can anyone help me with the A/C air flow question and the humidity control? And lastly, the installers told me I could always add a humidifier later if I found I needed it. Is that true? Will it work w/the xl950?