total air flow changes in multi zone system with VAV's and outside damper

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Old 07-08-12, 03:37 PM
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total air flow changes in multi zone system with VAV's and outside damper

on this system there are 4 zones and each shows the actual CFM,

The CFM amounts for each zone and overall tend to increase by 35% when the outside damper is opened from 0% to 50% (normally it is kept at 10%)

is this dramatic change due to inadequate internal return vent capacity?

also, with this air flow increase, due to increased outside damper opening, comes a higher discharge air temp from 65 to 69 degrees, and more humidity enters ducts from outside

is this normal, what can be done to improve air flow without decreasing the discharge temps?
 
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Old 07-08-12, 08:48 PM
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Sounds like you need more return
 
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Old 07-09-12, 08:06 AM
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more return

I tend to agree, thanks for comment
 
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