Space-Ray Infrared Radiant Tube Heater PTS Series Installation And Operation Instructions Manual page 40

In multiple heater applications, the combustion air intake may be ducted individually or common ducted in the same
configuration as shown for venting in Section 16.0. For combustion air intake duct sizing, please refer to the Vent
Sizing Table and use the diameter indicated, based on the number of heaters per duct.
Form #43343330
May 08 –39–