Page Title


This page contains recent updates to Municipal Codes that Rescom has been
 made aware of.

Posted 5/30/2005
City of Houston
New and revised return air requirement for City of Houston
This was revised by Richard Vrana to include the required free area for those who want to
use square duct or the cavity of a building for return air chase
The duct sizing is based on nominal size of the duct
 
Have confirmed sizing for return air ductwork per IRC as follows: 6 square inches for each
1000 Btu nominal cooling output rating.
Tonnage
 Duct Size
 Duct Size Sq.In.
 Required Sq.In.
1
 10"
 78.5"
 72.0"
1.5
 12"
 113.4"
 108.0"
2
 14"
 153.86"
 144.0"
2.5
 16"
 200.96"
 180.0"
3.0
 18"
 254.34"
 216.0"
3.5
 18"
 254.34"
 240.0"
4.0
 20"
 314.0"
 242.40"
5.0
 2 - 16"
 380.0"
 360.0"
Additionally, Houston now requires that a return air can be installed on the input side of a
horizontal air handler when connecting a return duct to the air handler. In other words they will
not accept a flat piece of duct-board or metal with the duct attached. 5/29/2005