Sterling QVES - Manual (Page 10)

10
VENTING
ANSI now organizes vented
appliances into four categories. Category I
Includes non-condensing
appliances with negative vent
pressure, like the traditional
atmospheric unit heater.
Category II
Groups condensing appliances
with negative vent pressure.
Category III
Appliances are non-condensing
and operate with a positive vent
pressure.
Category IV
Covers condensing appliances
with positive vent pressure.
NOTICE: Category II and IV do
not apply to equipment specifi ed
within this manual.
Venting Categories
Non
Condensing Condensing
Negative
Vent
I II
Pressure
Positive
Vent
III IV
Pressure