"I dunno about that one Justalurker, when I look at both the X-300 and X-500 specs, the X-500 is 3" longer overall (75" vs 72"), and the wheel-base is 51.2" vs 49.4" for the X-300" Look at the parts lists... the frame on the X500 and the X300 both sub to part # AM137099. you the hood is also the same. "With a 48" deck, the X-300 weighs 616 lbs, vs the X-500 at 760 lbs. No doubt though, the X-500's larger tires/wheels, larger engine and trans-axle, account for some of the 144 lb difference" Wheels, tires, K72 with larger oil capacity and 1" axles, larger engine, and the two piece body on the X500 instead of the smaller one piece body on the X300. "The X-500 is also 3" wider (approx), but that's probably due to the wider rear wheels/tires" X500 has hubs on the rear axles with bolt-on rims AND the offset of the 12" rims.

A properly sized unit should be able to maintain reasonable humidity levels (though maybe not at 78 degrees without a dehumidification mode). The dual-stage unit will help control humidity. The only way of extra dehumidification with the XL16i that I know of is with the TCONT803/Honeywell TH8321 thermostat, which will overcool to control humidity. Ask your contractor why he proposed the VisionPRO IAQ when the BK terminal is already in use by the XL16i, thus not allowing the dehumidification feature of the VisionPRO IAQ (which is great as it actually slows down the blower). If you want an alternative that can make use of the VisionPRO IAQ, I'd go with the XL15i. It's a single-stage unit, but sized properly it should control humidity fine with the added advantage of the VisionPRO IAQ. Here are possible setups (ask your contractor what size he would recommend--I would NOT go with a 3 ton for your size home). Now, there are different air handlers that can go with these units, but the 4TEE3F39 air handler is tall due to the Vortica blower. The 4TWX5024A1000A (2-ton XL15i) with the 4TEE3F31B1000A yields 13.00 EER, 15.25 SEER and 8.60 HSPF. The 4TWX5024A1000A (2-ton XL15i) with the 4TEE3F39A1000A yields 13.00 EER, 16.00 SEER, and 9.00 HSPF. The 4TWX5018A1000A (1.5-ton XL15i) with the 4TEE3F31B1000A (only rated match with the 1.5-ton outdoor unit) yields 13.00 EER, 15.00 HSPF, and 8.50 HSPF. Feel free to print out my responses if it will be easier for you to go over these possible issues with your contractor. Good luck.

See there. Learn something everyday. This proprietary jargon is getting ahead of me. Good deal. You are getting one fine system that should give you years of good service as well as comfort and savings compared to that oversized system you have now. A little knowledge goes a long way. IMO Here is a link that might be useful: Evolution Connex Controller

my plan is to figure out what i want. then design the specifics. then price it out. right now one thing i have ruled out is a heat pump-- my sister and BIL have that and i'm always uncomfortable in their house-- although they keep it at 72 degrees it never seems warm and is always drafty (i shouldn't have a closed mind about this, but that's the way it seems-- and their system is over 25 years old/ maybe technology has changed) diggerb