Tom

I have been following your other thread and I believe I said that for your area/climate, I recommended a matching var speed air handler paired with a HP rather than backup gas furnace.

There may be two obstacles to this type configuration.

1.size of air handler and its location

2.whether your electrical service/breaker panel requires an update to handle the backup electric strips.

and yes, you do require electric backup strips both for defrost function, aux heat when needed, and emergency heat if you have breakdown situation on outside HP condenser. If the electric service update is necessary but is cost prohibitive, then go with gas furnace backup-only 80% eff var speed would be more than adequate.

now to get on my soapbox for a minute. Trane is clearly falling behind on dual fuel applications.I would not want to leave $1500 on the table due to their shortcomings. I am not a Trane basher as I have a 4 yr old Trane dual fuel system and have generally been very pleased especially with my savings over gas. To date, I believe I have used about 60 therms of nat gas backup this winter as opposed to relying almost exclusively on my Trane HP. My Trane furnace is an XV90 that has been phased out for the XV95-93% eff vs 95% eff. I have never used the second stage on the furnace and really the furnace is overkill for my home along with my SE area/climate.

on a three ton Trane XL15i HP, there were 6 configurations that qualified for the tax credit-all with air handlers,none dual fuel.

on the Lennox three ton XP14 HP, there were about 18 configurations that qualified-both air handlers and gas furnace.(No XP15 HPs qualified at all)

and for Carrier's three ton Performance 15 "H" mdl, there were over 100 configurations that qualified-both air handler and gas furnace backup.

If you require the gas furnace backup, then you must look at the Carrier systems.

the gas fireplace backup is nice but it should not be depended on as the exclusive backup/emergency heat for your home.

let me know if you have questions.

IMO

I agree with all the above and am satisfied with my heat pump as well. A heat pump is probably the better choice for your area with those temperatures. Trane, Carrier, Lennox, and Rheem probably all have combinations fitting the requirements for efficiency in the 3 ton size. If A/C is rarely used and heat is used more then you may even consider upsizing a half ton to get a little more heat--not uncommon in areas where A/C is rarely used. By rarely I mean less than a month out of the year.