HVAC: Upgrading flex to rigid in the attic. Is it worth it?

ejwjzs9Malsotano writes:

Since I've moved into my house, I've noticed that the upstairs has pretty terrible ventilation. It stays quite warm in the summer, and much cooler in the winter.

I'm trying to track down some of the issues (like very little airflow coming from the vents), but after poking around in the attic, I couldn't help but notice these fairly long runs of flex used for the return air: http://imgur.com/a/SCe2q

I guess my question is, would replacing these with a proper rigid installation improve the situation much, or is it not a very strong bang-for-buck upgrade?

Yes, long flex runs particular when not sized, routed and supported properly will reduce airflow and reduce efficiency. Also, you are again correct that rigid ductwork is more efficient than flex. However the primary reason you are having comfort differences between upstairs and downstairs is that heat rises. If you fix the airflow so that you are getting the same comfort level on both floors then when your turn on the heat this fall, that extra airflow will cause your upstairs to really over heat. I recommend zoning the two floors using motorized dampers and separate thermostats. This will require professional design and installation. I do want to caution you in this area, zoning done right is one of the best things you will experience. However, if done wrong, can be a nightmare. Make sure your contractor has reference from other zoning jobs or you do other due diligence on the contractor.

- James Bowman
National Technical Manager – HVACR

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