First, I'd like to thank everyone for their help before. Reading these forums has been a great source of information. I do have a few more questions though.
We received 3 bids so far. Two from Lennox dealers and one from a Trane dealer.
After talking with the Lennox dealers, we felt very confident in their companies and ability to properly install our new furnace. Neither ran a load calculation but we figured that was just because we are going to install just a new furnace and not a new evaporator coil or condenser. Both companies tried to steer us away from adding a duct out to our garage and both said upgrading from a 3-ton to a 4-ton furnace wouldn't be beneficial. One even noticed we had a vent in our return air duct up in the attic. He said that was a bad thing. They both obviously had nothing but good things to say about Lennox.
The Trane dealer was a different story. The initial bid was over the phone, we were told adding a duct to the garage was doable, and going up to a 4-ton unit would be ok. The Trane dealer is a member of the BBB but not a member of ACCA and they have been around since '62. I think overall they are good and honest company and would probably install the furnace correctly.
My questions are:
1. Should we steer clear from a company that says it's ok to add a vent to a garage and increase the furnace tonnage without adding to the AC?
2. Does the furnace and AC size have to match to properly heat/cool a house?
3. I've read more good things about Trane compared to Lennox on this board.
Not to start an argument here but in this case would a Lennox be a better choice?
4. Do you need a 2-stage thermostat for a 2 stage, variable speed furnace?