Also, I almost forgot... I have an AprilAire 5000 EAC which has its own control module that is hooked up to the existing thermostat. How should this be integrated into the new setup?

I don't even get the indoor humidity when I press MORE. This thermostat has built-in humidity sensor, right? So how do I get a reading? I don't think we need automatic dehumidification in CT, but since we have a humidifer on the HP, shouldn't we be able to maintain RH level in heating season, rather than having to go to basement and turn the dial on the humidifier? At the very least it would be nice to have a reading of RH so we know if we need to run standalone humidifiers during the winter, and if they're putting out too much when we do run them. There's also a frost control option that's related to this. Any idea on how to set that up?

ryanhughes The reason I asked is that 2 ac contractors qouted me using the White-Rogers 1F95-1291. There both feel that in the dehumidifing setting you can accomplish the same as the IAQ. This may be hierarchy to some here. Thier manual relects the following: Programmable Dehumidification Optimal Comfort Mode (OC) or Optimal Dehumidification (Od) Â This item can be selected to OC (Optimal Comfort mode), Od (Optimal Dehumidification), or OFF. When Optimal Comfort (OC) is enabled, this feature automatically reduces indoor humidity with a call for Cooling if humidity is 2% above humidity setpoint. Humidity is set by pressing the Humidity key when in the appropriate mode, in this case Cooling, and pressing the or keys to set desired humidity (range 40% to 95%) level followed by pressing Humidity key again. This dehumidification feature uses less energy by maintaining temperature and dehumidifying only when a call for Cooling is required. Optimal Dehumidification (Od) when enabled, this feature automatically reduces indoor humidity with a call for Cooling if humidity is 2% above setting. Humidity is set by pressing the HUMIDITY key when in the appropriate mode, in this case Cooling, and pressing the or keys to set desired humidity level followed by pressing Humidity key again. This dehumidification feature may use more energy by making dehumidification a priority initiating a call for cooling if humidity is 2% above desired setting. This feature may also over-cool the condition space by up to 3 degrees to achieve the desired humidity level. (Note: Both dehumidification modes operate in Cooling mode only with a call for cooling) What do you think? Here is a link to the complete manual: http://www.white-rodgers.com/wrdhom/pdfs/instruction_sheets/0037-6914.pdf

I just set my Rheem VS air handler up to control humidity via the IAQ. You don't need anything else, unless you want to do it with absolutely no overcooling, in which case you need a relay. I chose to set it to one degree of overcooling instead, which is the lowest the IAQ goes. Rheem's ODD (On Demand Dehumidification) line works bassackwards compared to the rest of the industry, so you have to set the IAQ up as if you wanted to use overcooling to control humidity in order to get the DHM terminals to switch the ODD line properly. The IAQ could have a whole lot better programming interface. BTW, the crew that installed my equipment apparently didn't have a clue how to wire it for ODD, and just left it unwired, even though I told them the main reason I wanted the VS AH was humidity control. The good news is Rheem's ODD works wonderfully. It really drops the humidity when it comes on. I think you need the 9,000 series IAQ to do the ODD, but I don't have my paperwork handy to verify that.