He was going by the size of the existing furnace. He did say he thought it was way oversized, said didn't really need that big especially with a variable speed blower. I specifically asked him if it had demand defrost and he said yes, and explained it to me again. I did not ask if it was electronic, though. Are some of them not?

All units are Bryant Furnace = 355BAV A/C = 127A Heat Pump = 226A Had to order today to take advantage of rebate offer that ends 8/31. Never could figure out how to estimate the cost of running the heat pump vs. the gas furnace and couldn't locate any on-line calculators/spreadsheets that would help. Figured I'd save a bunch with new 95% furnace over the old sigle-stage 80%, and the new 17 SEER a/c over the old single-stage 10. It's small house (1450 sf) and well insulated, and I didn't know if I'd squeeze enough additional savings with a heat pump to justify the extra initial cost of the pump plus whatever extra cost would be involved in replacing it sooner because of running it much more. When in doubt, play conservatively (at least where money is involved), so I went for the a/c unit. Wish I'd discovered this website a month earlier. Thanks to all those who responded.

You are right on the cusp with a 20 yr old gas furnace of when the codes changedand the requirement of all gas equipment was for a minimum of 78% efficiency. That was '93. The question is, is yours one of the newer units or did they put in the older style. If the older, then you may be looking at a 60% efficient unit. Also, those being new designs there were some problems with those "new" units at the time. l guess after 20 yrs we can call your ok;) Although the previous owners remodeled I would make my mshp/furnace decision almost solely on the condition of the duct system. You need to have it pressure tested for leakage. Google "doeductleakage" to see what I am talking about. If the duct system passes muster then the new furnace is a choice. If it doesn't then it is not. It is not worth spending the money to repair it. I pulled all my ductowrk out and went mshp and Rinnai Energysaver (all Net to the space heating/cooling with no duct or duct losses) As a result, with the elimination of the ductwork I found two good size closets and a large storage area under the stairs and we are very comfortable.

A question for those who know more - is there an issue of pairing the coil (size/brand/airflow requirement or capacity) with an existing furnace? When I recently had new furnaces and AC put in, the contractor said that the expected "spec'd" furnace model for my house (in a mild winter area) didn't have enough airflow for the higher sized A/C coil and condenser needed. It was easy enough for him to use an appropriate model without upsizing the furnace output but it was a consideration. Back in the day of single stage furnaces you would have the gas heat blast effect for certain homes because the air flow needs for the AC were higher and pairing of a large furnace to meet those needs would result in blasting heat / short cycling of the furnace. Little you could do to rectify that problem back then. Many would use manual dampers and have to readjust them between spring and fall. They would often times sell maintenance plans based on this problem. However, this climate can some years be hot one minute and cold the next. Switch so often that you're doing the tango between areas of your home and the thermostat. (manual dampers are not a solution for that reason.) Now 2 stage gas furnaces rectifies this problem by running in low fire. If the furnace heat capacity is oversized for the home to operate the AC air flow needs it won't matter as the furnace will never run long enough to hit stage 2 high fire. Problem is occasionally you come across people who like the heat blast of older furnaces and complain the new furnace doesn't put out enough heat. There are ways to over come this as well, but you have to communicate often times to discover what the actual complaint is about.