We're converting our 300 sq ft garage into a family room. Trying to
decide between a running $2,000 worth of duct versus buying a $4,000
ductless mini-split system. My preference is to go duct and tap into
my central air.

But I am worried that it will be too warm in the summer. I've got a
dual-zone system. 1.5 ton for the 600 sq ft upstairs and 1.5 ton for
the 600 sq ft downstairs. Calculations show we have almost exactly 300
sq ft capacity left downstairs. It will be close.

Another thought: My Armstrong central air system is 13 years old. It
may be getting close to the end of its life. I am thinking about going
duct, and if it is too warm next summer, upgrading the end-of-life
Armstrong to a higher tonnage.

My question: How much does an average system replacement cost? I want
to replace both the condensor and evaporator coil.

Can you give me parts and labor seperate? I've got family in HVAC that
can do labor free if I provide enough beer.

Thanks,

Chris