Hard duct moves the air more efficiently. Flex duct creates some
turbulence and usually needs to be sized up to compensate. If the
quantity of insulation on the duct is the same, and if the joints
are well sealed, the hard duct would be better. Hard duct is most
often used for the main portion of the run and the last few feet
are often flex.
If the duct is in good condition. . . .
If the duct was sized properly the first time. . . ..
If the duct is insulated properly. ... ..
If the joints are sealed, including the connection to the
register. . ..
then the duct is probably not your problem.
Spend your time and dollars having a good technician run a Manual
J on your system. They should be able to tell you if the
existing system is sized properly. Assume for a moment that it
is, now you need to discuss why yours is not functioning properly.
You may need newer equipment or perhaps a good
cleaning/balancing/servicing will suffice.
Have the HVAC man show you through the manual J why you need to do
something different. Newer equipment with better Seer ratings
becomes good economics when he can show you the return on the
Keep the whole world singing . . . .
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