BL is right. The latent capacity (as a percentage of total capacity) tends to be lower during low stage operation, as is the case in just about all manufacturers' two-stage scroll compressor systems. The primary reason is the larger indoor coil volume with respect to the condenser output capacity. This is offset somewhat with the longer runtimes provided with a 2-stage unit, and the key is that you don't oversize 2-stage units such that they short cycle in low stage. Also, in my opinion as long as the 2-stage unit isn't (grossly) oversized as per the load calc, this issue is a bit less significant with the Trane Hyperion air handlers with the EEV (and the expanded performance data tend to show it, last I looked). The EEV does a good job accurately metering refrigerant flow under a wide array of operating load conditions to get the coil cold rather quickly and ready to dehumidify quite well. As BL also mentioned, with a good control like the Honeywell VP IAQ, you can have the system wired/configured to decrease airflow 20% when humidity is above set point -- this further increases latent capacity. A properly sized single-stage or two-stage unit should do a fine job dehumidifying. The two-stage unit will likely give you longer runtimes and greater comfort. A smart thermostat (as mentioned) is a great addition. This post was edited by ryanhughes on Wed, Mar 12, 14 at 14:43

Goat That furnace is a two stg 80% eff var speed XV80 model. If you expect full functionality of this furnace, then you will require a true two stg thermostat. If you use old thermostat, then furnace will run on high stg all the time. Not very smart. I did check and the system quoted is a match. 29 KBTUs cooling, 13 EER, 16 SEER. As stated furnace has two stages, 31 KBTU on low, 48 KBTU on high. I suggest upgrading to the XV95 furnace mdl for it's higher efficiency. You want a new and correctly sized refrigerant lineset and I would recommend a whole house air filter cabinet if you don't have one. BTW, what size and eff is your existing furnace? IMO

I would pay $100 for Trane's Perfect Fit Media filter Cabinet. It is very heavy duty compared to the Honeywell and sized to fit the furnace like a hand fits a glove. Less about the filters and more about the fit and quality of cabinet. I do believe the Trane takes a 5" filter, the HW a 4" filter. BTW, I have the Trane. Very easy to replace old filter. As far as thermostat, first choice would be HW VP Prestige IAQ, 2nd choice would be HW Mdl 8321 (same as Trane 803).. I like the IAQ because it is a true two stage thermostat, has dehumidify on demand feature for AC cooling, and can handle the control of an add on HW humidifier. Discuss carefully with your dealer. This is a nice system you are getting. The AHRI directory site is down for maintenance or else I would look up the matching AHRI number. I would ask dealer to give you the matching number and the performance/efficiency numbers for AC. Still believe you should get a quote on a Carrier Infinity. IMO

Thanks... We have to go with 80% due to the location and height of the room. I have been told that the system (Variable 2 stage furnace) most likely does qualify if paired with the XR15. Also told that the IAQ is not needed with the above system as it doesn't give any benefit if not paired up with a two stage a/c unit. Also, one guy quoted an 80BTU and the other a 100BTU, not sure why they have quoted them differently?