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Install & Replace

Changing the air flow from central AC/heat ducts


I'm looking for a do-it-yourself method for changing the air flow in my home's central AC/heating. The vents to the bedrooms flow like a wind storm, while the ones to the main living areas barely flow.


Adjusting the air entrance to the rooms does nothing but make the windstorm louder. 


My home is new (three years old) and the entire system and ductwork is in the attic. 




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Posted 2012-10-31T02:01:24+0000  by marylynnc11 marylynnc11

Short of redoing all your duct work by a licensed contractor there are a few things you can do to help pull air to a low flow area. There are in-line fans that can be installed. There are also units that can be added atop of registers that have a fan and will pull the air to and out that register. The latter units can be found with the register covers in your local THD. I believe they're call something like a register booster and cost around $35.

Equalizer EQ2 Heating and Air Conditioning Register Booster

Posted 2012-10-31T20:32:42+0000  by Paul

Hi Mary ,


It sounds like your system is not sized or balanced properly.


Heated and cooled air in your home is forced thru the duct system via furnace blower/fan. If the main duct system (main trunk) and take offs (lines going to the rooms) are not properly sized or positioned within the system an air velocity increases and creates that "windstorm” noise.


If you take a look at the duct system in your attic you will see a large duct and a number of small ducts branching off of it.

 Take off lines (small duct) that are closer to the furnace face higher air velocity than the ones at the very end of the system.

In your case bedrooms are probably the ones bellow  the furnace and living room is the one at the other end of the house.

All lines, per code, should have something called damper installed right after (6"-10") they branch of the main trunk.


Damper is basically an adjustable "gate" that is placed inside the pipe…


When you get up in the attic, see if you can locate one and adjust it a bit. If not than obviously you would have to have them installed.

Adjusting air at the registers is going to reduce the flow but not the noise. When adjusted with dampers air flow bounces right back in to the main trunk.

Before I get in to how to install one, (it could be a DIY project) I would ask you post back and confirm if all above it is the case.

On a side note… you may want to consider investing in to one of these CFM meters that measures air coming out of the registers so that you can balance you system equally and to your comfort.

 CFM meter.jpg

Hope this helps,




Posted 2012-11-13T16:38:40+0000  by George_HD_CHI
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