lower level cooling issue

Hi,

I recently purchased a new home with two zone ac one covers the upper levels and one covers the lower level. I have been having an issue balancing the lower level unit airflow. One room is very cold with very high flow and other rooms on the lower level are warmer with much lower airflow.

When I checked in the attic, the higher flow room ducts are much closer to the output from the air handler than the ducts I am having low flow which sit at the end of the header.

I am not a professional so I would appreciate guidance on fixing this.

Was also wondering about operating the system with respect to running both units or only one at a time. It seems in the heat of the day, I need to run both to keep the house cool. Note both air handlers and returns are in the center hall and reside in the attic.

thx

So its two units? Not a zoned single system?

Sounds like its time to get the downstairs unit checked out. Could be a pleathera of things.

yes, two separate units, with one zone upstairs and one down. The system is only one season old but with out any data...the downstairs unit seems undersized.

thanks for the response doc

have dampers put in all the down stairs runs so you can balance it out. with out then you will waist your time tring.

thanks tinknocker ,,,, are dampers someting to install in the attic correct? I have flexible runs up there now. Any specs or product you like?

thx for the response.BDX

Yes, volume control dampers in the takeoffs near the trunk line are the best way to control airflow for balancing. There also may be an issue of where the takeoffs are located in the trunk system. A decent hvac contractor should be able to evaluate the system and give you information on what is necessary and the cost involved. Unless the duct system has major issues it shouldn't be a terribly expensive fix. Most contractors give free estimates.

the flex runs are attached to collars on the main trunk duct. the dampers go in these collars if they are not all ready in them. most companies but the collars with the dampers already in them. if you close them dont close them all the way and not the end ones since thay are the ones you need air in. also if they are in already make sure they are all open first. some have handles. against the pipe is closed and with the pipe is open. some have a screw driver slot. same thing with is open across is closed
they all have lock nuts so they will stay where they are set. sometimes they are not tightened and the damper is pushed closed by the air

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Originally posted by bdx
yes, two separate units, with one zone upstairs and one down. The system is only one season old but with out any data...the downstairs unit seems undersized.

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I would verify the system performance before I just arbitrarily agreed and conceeded to the notion of a larger unit. It may just need a simple service.