AC room problem

[David Duong]

Hi -

Does anyone have ideas or suggestions? I purchased a rental property and had the whole AC unit replaced (ducts were not replaced, however). All rooms receive cold air except the master bedroom. The master receives little to no air. My AC guy went up to the attic and did a cursory review; he stated that did not see that any of the AC ducts were pinched. I suspect, however, if everyone room is receiving cold air except for the master bedroom, one of the air ducts feeding the mater must be pinched somewhere, blocked, has holes in it, or it became lose from the main duct. I also read on-line that may be the damper is shut somewhere (not sure what that means, however).

I'll call you to discuss, but I'm hoping you know someone that’s good in checking AC ducts that I can call, talk to, and use. Let me know if you think it might be something else. Thanks.

Any help is appreciated. Thanks.

[Dave Barnard]

David,
Assuming your AC guy did a thorough check, and there's nothing physically wrong with the ducting, it is likely a design flaw. Air takes the path of least resistance, which means the shortest ducts (closest to the air handler) will naturally get more flow than the ducts further away, as Mitch stated. I'm not sure what area your home is in, but here in southern CA most track homes use flex duct that was typically installed by the lowest bidder. If the size of the room and length of duct needed to get there were not compensated for, then the end result is what your experiencing.

You can install manual dampers in the ducting system which can be used to balance the air-flow. With these dampers you can restrict air to the areas that are a little cooler wich will force more air to the areas that are warmer.

You may also consider a "duct booster". This is a motorized fan that gets installed in the duct that feeds the problem area which will run only when there is a call for heat or cool from the thermostat. This fan will supply the room with more air.

A much more expensive option, and not likely for you to consider given this is a rental, would be to install a zoning system. This system has motorized dampers that are operated by individual thermostats. You can have 2 zones or as many as you would like. You can actually achieve different temperatures in different parts of the house while only having one a/c system.

If you would like to chat, send me your contact info and I'll call you tomorrow.

Dave