Airflow weak to 3rd level


Old 01-12-11, 05:11 PM
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Join Date: Dec 2010
Location: USA
Posts: 42
Airflow weak to 3rd level

I have a problem in cooling season with weak airflow to the upper level of a three level townhouse. The temperature differential between 1st and 3rd floors is 10-12 degrees.

The design of the duct system is a flat main duct between 1st and 2nd levels. It has round branch ducts branching off to the registers. On the 1st and 2nd levels each register has its own duct run.

Going up to the 3rd level it seems like several registers are combined on the same duct runs. The airflow is very weak and the only way to get the 3rd level reasonably comfortable is to run the bathroom exhaust fans to pull out some of the humidity and heat in the early evening. I have tried register fans and they dont lower the temp and only make a lot of noise instead.

I have thought about adding a second system and ductwork in the attic for the third level. Before I seriously consider this, are there any other suggestions on how to improve this situation?

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Old 01-14-11, 11:51 AM
airman.1994's Avatar
Join Date: Dec 2005
Location: VA
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2 systems on a three story house is best! Only other option is two rework all the duct work. Cheapest way would be to add the 2nd system. What part of VA?
Old 01-14-11, 01:46 PM
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Join Date: Dec 2010
Location: USA
Posts: 42
It is about 650sf on the 3rd level. Would I need a HP or just an AC unit? Any estimate of the cost?

PS I also have a problem in the winter on the first level. It is a flippin 10 degrees colder (mid 50's) than the 3rd level. All the heat rises to the 3rd floor.

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