What are you looking for? The XL18i system is a two stage system, the XL15i system is single stage. The selection of the size of the air handler is very important for best performance/efficiency numbers. 4655313 Active Systems XL15I WEATHERTRON TRANE 4TWX5036B1 *AM7A0C36H31 1225 37600 12.50 15.00 34600 9.25 21800 1 HRCU-A-CB Yes 311 751 Yes TAM7 36 size for the 3 ton XL15i system. 7117217 Active Systems TRANE XL18I TRANE 4TWX8036C1 *AM7A0C42H31 1185 945 37000 13.00 18.00 31400 9.50 20200 1 HRCU-A-CB 255 627 Yes TAM7 42 size for the 3 ton XL18i system. If this is not a budget decision, then get the XL18i system as I listed with 10 KW heat strip. Pay attention to the air handler model/size. If you are able to interpret the AhRI numbers, you can readily see there are some marginal savings with the XL18i system on cooling and good savings on heating with the higher HSPF efficiency. You are getting some very good pricing. I am done here. IMO Good Luck This post was edited by tigerdunes on Tue, May 20, 14 at 6:37

Quote 1: Does not qualify for the tax credit, if that's what they're leading you to believe. Good outdoor unit, but it bothers me they are not including a variable speed air handler. Quote 2: This company may just have a lower overhead and overall lower prices. If your realtor has had good experience in the past, I wouldn't have a problem. But I would suggest stepping the outdoor unit up to the Amana line (subsidiary of Goodman), which is a more premium product to compare to the other units you've been quoted. In general I would avoid Goodman/Amana because I think there's better out there, but if it's what fits the space and qualifies for the tax credit, then it would be worth considering. The Carrier units that would qualify are huge physically outside. Quote 4: Sounds like they're oversizing the equipment--not a good thing. I would avoid. 800 sqft. in our area shouldn't require 2 tons, and if the old 1.5 ton did the job in the past, that's what I'd install. Also they are not informing you that if you register the units with Trane within 60 days of install, warranty should be 10 years on all parts. And yes, a humidifier should give an added sense of warmth to the air and hence allow you to set your thermostat lower.

"slk230red, thank you for your input. I also want to stay with the single speed. If all goes well with this install I will replace the unit on the other side of the house once it stops putting out cold air. galen68, I will post an update once I have chosen the AH and HP." "Had the 2 Ton XR14 AC and 2 Ton TEM4 AH installed with a 5k heat strip. This is exactly what we had with the old unit. Heating is not an issue in Phoenix. Mild winters, heat hardly used. Even on coldest mornings it is on for an hour at most and I turn off completely at night. I read turning off at night would be a big issue with a HP as they say to leave it on and forget it. Why leave the heat on if I am not comfortable? My avg elec bill in winter for 2500sf home w/pool filter on 8hrs every day averages around $120. Not worth the extra $10-30 I could save with a HP, being comfortable is worth the extra $. I am extremely happy with whisper quiet TEM4. Maybe from an hvac point of view it may not make sense but I am happy with my decision." Hi roxan, glad things worked out and that you're enjoying your new XR14/TEM4 system. Be sure to check that your new units are registered on the Trane warranty website to receive the 10 yr. parts warranty. My dealer likes to wait a week or two to make sure everything is working properly, I just checked and everything is registered. He offered to remove and replace anything if I wasn't fully satisfied. Also, there was no money down and he didn't even want full payment until I was completely satisfied. On another note, here is some information I received from someone I know in another state who advised me to get the TEM4 AH: "I recommend the TEM4- non variable or TEM6/7 variable AH. The TAM7 is a plastic cabinet with all new components. To make a long story short, get the TEM4 or TEM6, it's tried and true. The TAM7 is a basket case plagued with problems. Has three different color led lights flashing fault codes known around here as the Christmas tree effect. Unreliable sensors etc. not all 7's go boom but enough that some Trane dealers won't install them anymore. Including me."

I am confused as to what you currently have. You mentioned you an electric furnace and a heat pump. Then you talk about moving to propane instead of a heat pump. In your first post you said your current heat pump is 2 tons, but in a latter post you said it is 2.5 tons. It is hard to believe that you can increase your heat pump to 4 tons without increasing the main supply and return. Perhaps your duct work was originally the proper size, but someone install an undersized heat pump. If you want some advice, then please describe the size of your house, and exactly how you heat your house now. Heat pumps are sized by cooling loads and not heating. The winter design temperature for Columbus is 6F degrees, but it can drop to much lower temperatures. You need a properly sized heat pump with a back up heat source. That heat source could be electric heat strips or a propane furnace. If you post your electric rate and the price you pay for propane, a calculation can be done to compare the heating costs.