I had posted this morning asking about rebate programs. Looks like Carrier has a $1200 rebate program going. The Bryant website mentions a $1100 rebate. I think you have to go to a participating dealer, the rebate isn't available through all dealers.

The following link is to Consumer Reports reliability ratings on furnaces, and there's no statistically meaningful difference between them accoring to CR. I haven't found their ratings for central air units, they many not have any.

http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/gas-furnaces/furnaces-repair-history-205/overview/

Has any contractor determined what your home loads out to in terms of heating and a/c? The 70k vs. 80k issue is a matter of manufacturer differences. Usually when furnaces are sized to Manual J a 20% safety factor should be added anyway, so perhaps the difference compared to your heat loss figure isn't an issue. Still important for a load calculation to be done.

You're comparing two good systems. Yes, the Lennox does have more stages of heating than the Trane, so it will provide more comfort. Both the XL15i and XC15 are very quiet. The IAQ is a good thermostat. I think it's going to come down to who's the better dealer.

Other brands I'd look at are Carrier and Rheem (or Bryant and Ruud) if there are dealers of such brands in your area (likely there are) and you are willing to get additional quotes.

Re: the Manual J. The only one that claims to have done a heat load calc is the Lennox dealer I like. I'm a bit confused by the result they came up with though as it was quoted as a "minimum of about 32,000 BTUH." Lennox makes a 70K gross, 66,500 net and Trane makes an 80K gross, 76K net furnace. Our current model is a 75K gross, 60K net, which heats the house just fine so I think the Lennox is a better fit, especially considering the multiple stages of regulation.

Being the engineer I am I may do my own calc since I have all the measurements. Took at look at a little program called Heat Calc and for $49 it may be worth doing a detailed calculation, although all four dealers essentially proposed the same size units (2300 sq ft, 2-story). Would be nice to see how the loads change with different attic and subloor R-values, both of which are in bad condition now.

Lennox dealer says they used to sell Trane. He claims the local distributor never stocked what they needed. Lennox has their own factory stocked warehouse in Seattle.

Lennox dealer is also MUCH more responsive to my questions and has been very helpful. Other guys don't seem nearly as interested.

Looks like I will go with Lennox.

Looks like the Lennox dealer gave you the cooling load, which puts you around a 3 ton unit. It also seems that the Lennox would be a better fit furnace if your old 60k output did the job just fine. You can always request that a heat loss figure after you sign the contract, but if the old furnace did the job well and did NOT short cycle, and the G71MP has multiple stages of heating, it's probably the best match.

Parts availability is an important aspect. However that is one dealer's experience and opinion. There may be other distributors. In some areas, Lennox parts are harder to obtain than others. Considering the amount of Lennox I see around my area, I'd say parts aren't a problem where I am either.

Coil model number provided for the Lennox setup? The CX34-43 is a good match: 12.7 EER, 15.5 SEER.

Does that 95% AFUE qualify you for the $1500 tax credit? I think it should...

The load of 32,000 BTUH was mentioned as a heating load and that they were allowed to go up to twice the calculated load. Our old furnace does tend to short cycle at times unless it's trying to warm the house from the overnight setback. Don't know if that's a function of the furnace itself (single speed, one stage, bottom of the line Heil), the thermostat, or the way it's set up.

Last December was about as cold as it ever gets around here and there where times when the furnace ran nearly non-stop, but keep in mind about 2/3 of the walls downstairs are bare and down to the studs with no insulation during our remodeling. This is really why I want to double check both the heating and cooling loads, but it seems a 70K BTUH gross rating is appropriate as that would allow the furnace to modulate as needed. If the rating were too low it would be on the highest stage much more of the time.

Coil number quoted was a CR-33-48C-4. I can't find any ARI numbers with that coil. I was told downdraft furnaces do not do as well. If we could get 12.7 EER and 15.5 SEER that would be higher than what they are telling me now, which is about 12.2, 14.5.

Yes, the 070 is the smallest G71MP furnace.

Ok, the CR33 is the downflow coil. The CX34 is actually upflow only (my mistake). Here is Lennox's combination rating data for that matchup:

G71MPP-36B-070
CR33-48B-F
XC15-036-230
35,200 btu's cooling, 12 EER, 14.2 SEER

tom

I still believe high eff HP with air handler is your best choice from an operating cost view. however, if you elect high eff furnace with AC, please don't leave that $1500 tax credit lying on the table. that would be a big mistake.

IMO

The G71MPP is 95% efficient in all four installation configurations, so there's the $1500 tax credit.

One of the contractors looked into an air handler + HP. We have a 200A panel, but he didn't think there was enough space remaining to power electric backup heating. I suppose it may be worth a 2nd look.

But as Ryan Hughes points out, the G71 is 95% AFUE so the $1500 tax credit is fine. Would also get $350 back from my local utility. I'm not even sure we could come up with a HP + air handler combination that meets the Tier 2 specs for the tax credit with our downdraft configuration.