After reading more carefully, it seems your sizing estimates are all over the place, from 2.5 ton (Lennox), to 3 ton (Trane), to 4 ton (Rheem). A properly done load calculation is necessary to get the equipment size right, especially since you've made changes to your home's structure. Now would also be a good time to have your ductwork balanced so that each room gets the required airflow per the load calculation. Before investing money in a new system, it is very important to ensure your new system is operating at its rated capacity and efficiency.

A test like that is not accurate unless the parameters are tightly controlled and all contributing factors noted. The meter reading includes all household electric use, not just the heat pump. Cooking? Bathing? Dishwashing? Laundry? Sunshine vs. overcast? Wet vs. dry weather (affects heat pump defrost frequency)? Did the 3°F recovery involve use of auxiliary heat strips? 2°F and 3°F setback is very minimal. More savings is potentially garnered with larger setbacks. I'm in TX. We had a rare snowfall during a wet norther on Dec 4. After that Dec 4 weather incident, I didn't run the central heating (heat pump) for several weeks. Instead, I used a space heater only in the bedroom at night. I noted that even with occasional nighttime temps into the upper 30°Fs, the unheated rooms in my house rarely dropped below 60°F. So ... if I had been running the heat pump at 70°F normal with a 2°F setback (68°F), it still would run to maintain 68°F during the setback periods ... but an 8°F to 10°F setback (setpoint of 62°F or 60°F), it would run very little during the setback periods, if at all. That'd make a difference on KWH usage in regards to setback vs. none.

Short cycling occurs when the AC has much more capacity than the heat load of the house. The AC turns on and cools the house very quickly. Quickly could mean 10 - 20 minutes. The short amount of time does not allow the AC to lower the indoor humidity. You feel cool but your are still sweating. It becomes a problem if you live in an area which has high humidity. The 5 ton capacity refers the size of the condenser. The blower in the air handler is adjusted to work with various condenser sizes. Your handler may be able to work with a smaller condenser. I don't have a good feeling about the installation contractor. He has done a poor installation and appears to be avoiding you. What type of warranty does he provide? Make sure you document the problems and stay on top of him.

>> Hope to hear an update from the original poster of the thread soon as well. Hi, still here. :) Yeah, so far, none of the contractors have proposed a 'mismatched' coil and condenser. One said 5/5, but all the others have been 4/4 so far. No load calcs yet. One contractor said he'd do it if there were a commitment to go with them. So if they commit to dropping their price and changing some of the equip to match better proposals from others, then we may have something.. :) [unfortunately, although they had a polished sales presentation, their bid missed a couple elements with regard to equipment, including the low voltage wiring and the mismatched coil size (width)] I did see that the 4-ton XL15i requires the 7/8" x 3/8", so looks like I'm good. (phew) A contractor on Friday also said I'd need additional wiring to hook up a heat pump outside, so looks like it was missed by the one proposal. I think this has been asked before, but is the TL900 the same as the VisionPRO IAQ? I have two more contractors coming Monday, so after that will hopefully have all the information I need to start discussing it further with 1 or 2 and start negotiating equipment and price details. On related topics: There have been other differences in proposals, with some suggesting/including a replacement condenser pad, some not. I currently have what looks like an interlocking plastic condenser pad. Doesn't appear damaged, although may be slightly out-of-level (will be checking to make sure). Surrounded by bushes that I keep in check, and mulched w/ weeding done when needed. I understand concrete is the best option, but doubt the pads being included in some of the bids are much better than what I have. I'll be doing my own check to confirm what I have would fit the new condenser/heat pump. And, some are including an Electrical Disconnect/Fuse rewiring, some not. There's currently a disconnect (no fuse) connected to a 40amp double pole circuit breaker. One guy told me "that should be enough, but if it isn't and it trips a lot, we'll fix it free of charge" or something to the effect; which I'm not sure whether it's a good deal that he's not trying to sell me something I don't need or a caution flag that he doesn't know if it's sufficient.. The XL15i documentation says "Min Cir Ampacity = 30" and "Max Fuse Size (Amps) = 50", so I'm not sure whether that means the 40amp circuit breaker is sufficient or not.