landosand

pls re-verify mdl and mdl number of the Trane furnace and provide the evap coil model number.

you do want a system that takes advantage of the fed govt tax credit of up to $1500.

you are replacing an existing three ton model condenser and furnace?

There are several factors to consider:

1.availability
2.budget/cost
3.tax credit qualified
4.how long you expect to be in this home
5.warranty
6.brand reputation/reliability
7.dealer reputation
8.ductwork condition, size, insulation,etc

to your questions.

1.on return, you generally need enough return to move a minimum of 400 CFMs/ton. in your case, I would recommend a minimum of 1300 CFMs. Ask dealer what you have now. you do not want to be undersized on return. adding return or enlarging existing is usually a relatively inexpensive proposition.

2.I will wait to hear back from you on the Trane model numbers before commenting on price. I would not have Goodman unless that was all I could afford.

2a. if sized correctly, heat Pumps are a great idea for your area/climate.

I would say both furnaces quoted are too large for your home.

IMO

I would suspect that a 15/16 SEER HP would be capable of producing usable heat down to 32F without much trouble. I have a Trane 14 SEER unit that does just fine and I live in Northern VA.

Ditto on not having a Goodman system. I'm having to replace a Goodman heatpump due to leaks, corrosion, etc. that is only 6 years old....

For your mild climate, I'm surprised such a large furnace is being quoted (remember that it is a condensing, 90+ efficient furnace as well). Did these contractors do a load calc to determine/justify their sizing proposals? The fact that they are concerned with the ductwork is great, but system sizing is equally important. It doesn't make senes to me that the Goodman option costs more than the Trane option. Goodman equipment is relatively inexpensive (not saying it won't perform as well as the Trane would, because it should if installed correctly), so perhaps the Goodman dealer includes a broader scope of work?

The specific Trane gas furnace model number is XV95. We will get the tax credit for this unit.

The proposal lists the coil as: 4TXFH042

Cooling spec is 36,000 BTUs
Heating is 100,000 BTUs

We do have cathedral ceilings throughout our home. Would that justify the larger unit?

We are about to commit on the Trane so any last minute advice will be so much appreciated.

Gas furnace sounds way oversized for an 1800 sq ft home in Carolina, unless there is no insulation in the house.

Did anyone do a Manual J heat gain/loss calc for equipment sizing? If not, better get one done.

Good luck.

landosand

If you are certain that a three ton is satisfactory and correct size, then I would drop down to the next size furnace. Of course the only way to be positive is to have dealer perform a Man J heat/cool load calculation. I would encourage you to consider a 4-5" media cabinet for air filtration and select the Trane 803 stat or even better the HW VP IAQ stat that has DOD feature.

Did you decide on HP or straight AC? BTW, what size furnace is existing?

I really think a 95% eff furnace with HP is overkill for your area/climate but you probably need the 95 with Trane to qualify for the tax credit.

Best of luck!
IMO

What was the output of the old unit and did it provide the comfort levels you want?

A Manual J on an older house requires a lot of work to be accurate.

IR pictures and blower door tests unless you want to guess at R values and leakage.

The performance of the old unit (based on output capacity, NOT input) is a good metric.

Last year Consumer Reports listed a few comments on furnace reliability. Trane was the most reliable and Goodman was listed as needing more repairs than most. If I remember correctly, Goodman was at the bottom of the list for reliability. The engineering college I work at uses Trane AC equipment exclusively. Hope that helps.

I would have to vote for the Trane.