Glad to have found this forum, hopefully some of the experts/pros here can chime in with a response to my post. With Nat Gas prices going way up, and the fact I have a 30+ year old (Singer) unit running, I decided I better look into replacing the furnace sooner rather than later. Since my experience in this area is pretty limited to just maintaining this old unit, I am at a bit of a disadvantage on the subject. A couple of things I am trying to do.

1)Get a general sense on how much my energy savings will be by going from this old 60% AFUE Unit (100,000 Btu) to a new unit.

2)Try to pick out a dealer/brand I can trust in terms of quality workmanship and a fair price. Carrier & Trane are the 2 most significant brands I am aware of. (Due to the nice big marketing campaigns they put on). Basically trying to avoid getting screwed with either bad equipment/dealer/price.

Part 1: When attempting to determine how much I may save by upgrading, I downloaded the last 5 years worth of gas & Electric data on a month by month basis from We-energies. I was able to factor out the gas usage for the dryer & water heater using that data, but now I am just wondering if I have the following part correct.

Going from a 100K to 60K unit (40% less usage top start with), then factor a 30% improvement in efficiency over the old unit.
Feb of 2005 we used 120 Therms of gas for Heating the house. So the equation would look like this: (120*.60)*.70 =50.4 therms with new system. Now my initial guess is that the 40% reduction in usage due to the size correction is likely to be an over estimate, and not in fact a 1 to 1 relationship. But what should I factor for it then? Also is it reasonable to use the 30% improvement due to the better AFUE, or should I back that off a tad?

Part 2: So I called a Local Carrier Dealer here in Milwaukee, WI and had him come over and give me an estimate. Fist off he stated that the 100K Btu unit was much too big for my house. 1200 Sq Ft Cape Cod 1 ˝ story type. The unit he recommended is a 60K Btu 90%+ AFUE (58MCB- a “builders” series of the 58MCA, only “real” difference being warranty of 20 years on heat exchanger VS Lifetime, and a different front on it.) The Quote also included a Bypass Humidifier & High Efficient Air Filter, Condensate Pump plus all the usual extras/basics. My Electric is good, Ductwork is good, Thermostat is good. Central Air unit quoted is a 38TKB 2 ton/24K btu Carrier.
From what little I can tell this dealer has a “good” reputation here in this area.

A few people I have talked to felt my quote was “kinda high” sounding to them. One of them recently had a new furnace & A/C unit put in, in a bigger home for less (~$XXX, which was a 3 ton A/C Unit, but upon further looking into it, he got a Ducane 80% AFUE unit, and the A/C is a Concord, some brand I had never heard of, or read about, but his system seems to be doing a fine job for him so far. But the systems being quoted really aren’t apples to apples). This did make me wonder however, should I be just looking at a 80% AFUE? Can I mix a different/less expensive brand of A/C Unit with a Carrier Furnace? For that matter should I? Is a Carrier Furnace worth Twice the Price of a Concord? Should I be looking at a different brand, as far a the better price/performance/reliability mix?

My Sincere thanks in advance to those who respond with any help/ideas.