I recently had 2 places out to give me an estimate on a new Trane XL-16i heat pump system. The first place included air balancing (and duct cleaning) in their proposal. The second place told me that air balancing a duct system that isn't new (my house is 13 years old) has a minimal effect on comfort, especially with helping to fix a notoriously cold/hot room above a garage. For new duct systems, this place installs balance dampers in all of the lines. The second place seemed very knowledgeable with what they were saying and are air balance certified with NCI (I do not know if the first company is certified). He said that much of the increased comfort will come from the variable speed air handler and the increase in the amount of air (1200-1400 CFM) being pushed out of the air handler. The second place has a long check list of items they check once a system is installed (including static pressure, air flow, etc). Plus a big plus with the second place is that they have a 100% satisfaction guarantee as well as an unblemished BBB record (First place is bigger and has had 4 complaints over the past 3 years). The first place said that it would take 1-1.5 days to do the installation while the second place is saying 2-3 days. Basically I was wondering if the second place knows what they are talking about in regards to air balancing. Does air balancing an existing system something I should strive for with an install?