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Designs, materials, weights and performance ratings are approximate and subject to change without notice. Visit
armstrong
international.com for up-to-date information.
18
Installing Intake Air Ducting
Using outside air is
required
.
Duct diameter must be at least
as large as intake diameter on
blower. 15% diameter increase
is recommended every 10 feet
removed from heater.
Material can be:
• CPVC
• Galvanized sheet metal
• Single wall stainless steel
Note:
Do not
use manifold connected to other appliances.
Do not
run heater under negative air pressure.
Typical enclosure in sheet
metal box with screen.
Provide independent
support for duct. Do not
rest weight on blower
inlet.
Roof
Wall
Top must be solid metal.
Bird screen required.
Flexible connector
required.
