Jt Some questions please. What is your location? What size home living area? What size furnace and eff are you replacing? What size AC are you replacing? I would like to know the exact mdl number evap coil for each quote. What thermostat is proposed for the Carrier quote? That is a big difference between the 96% eff Carrier furnace and the 80% eff Trane furnace-both 60 K input. That would be about 56 KBTUs output on the Carrier and about 48 KBTUs on the Trane. Not insignificant. I don't care for some shortcuts that homeowners make particularly on reusing linesets and using existing thermostats that shortchange a nice furnace's operational capability. Post back with the info requested. IMO

If we did the job, it is a 99% chance that we would NOT replace the outdoor unit without replacing the indoor coil, the refrigerant line-set, and possibly a digital thermostat. IF, the existing indoor coil is rated 13 SEER or higher, then we would possibly replace just the outdoor unit. If the existing unit is 10 SEER, and the indoor coil is rated at 10 SEER, and we installed a 13 SEER or higher outdoor unit, the warranty on the outdoor unit is -0- days. If we replaced the outdoor unit and the indoor coil, and not the line-set, it is probable that the existing line-set will be to small. If our customer's budget would allow, we would recommend installing a 13 SEER heat pump instead of an A/C unit. Also, your smaller unit is a 2.5 ton unit. The "030" means 30,000 BTU. The "3" afterwards means 208/230 volts. The "0" is the series. And, the "1" is the packaging. The "38CKB" means that it is an electic air conditioning unit. Finally, our price to replace the system, not including the furnace, would be around $5,000.00. Hope this helps.... Phillip

Here are some features I think are important: - ability to set at least 4 temperature time periods per day - 7 day programing - temporary temperature override - true 2-stage control (if getting a 2-stage furnace/AC) - AC powered with battery back up - dehumidify on demand (if getting a variable speed furnace) I have the Infinity controller, here are some features which may not be present in other thermostats - static pressure reading - filter change alert - outside temperaure display - fault code display and logging - fan RPM display - maintenance reminder - installer diagnostic settings I believe the Trane TCONT900 is a good thermostat from what I have read. I don't see it listed on the Trane web site so I don't know if it is an older model. The XL900 seems to have the features you would want if you are getting a 2-stage furnace and AC. If you are getting the Infinity furnace then you need to get the Infinity controller. I own Carrier equipment and have been pleased so far with the comfort and performance. The Trane equipment is a good alternative.

mike_home, you make the perfect argument for why Manual J should be mandatory for all HVAC contractors. It would protect the customer from hacks and unscrupulous contractors. Smaller equipment means less cost for electricity over the life of the AC unit and less cost up front which saves the buyer money. The electricity savings is why the utility companies and many states are making it part of their mandatory requirements to have their HVAC contractors perform Manual J. Here's a good explanation from Dean Heating and Cooling on HVAC Talk Forum that explains the benefits of using a Manual J and also talking about proper duct design (Manual D). "A load calculation known as Manual J is the only correct way to determine heat loss and heat gain. Once equipment size has been determined, the duct system is designed by Manual D. These are design protocols formulated by ACCA. Duct design takes into account the location and potential gain (or loss) of having ducts in an attic, crawlspace, or even exposed on a roof. You are correct the installing a larger air conditioner on an undersized duct system is pointless. We have all seen it many times. Frequently, putting in smaller equipment delivers greater comfort when the existing equipment is too big. For example, a 4 ton unit on a 2.5 ton duct system can only deliver 2.5 tons worth of air flow. The oversized equipment still uses the electricity for 4 tons of cooling but the delivery system still limits what arrives in the space. The equipment actually uses more energy because of inadequate air flow. Plus it cycles more often than smaller equipment so its life is shortened." Here's a good discussion about Manual J calculations also from the HVAC Talk forum. There's an HVAC designer and an HVAC contractor that post over there that seem to have the most input on Manual J. Their user names are "dan sw fl" (AKA Designer Dan) and lkapigian.