Designer Guide

13
LOCHINVAR, LLC
300 MADDOX SIMPSON PKWY
LEBANON, TN 37090
www.lochinvar.com
Designer’s Guide / Knight XL Boiler
1. COMBUSTION AIR FROM OUTSIDE
If air is taken directly from outside the building with no
duct, provide two permanent openings to the equipment
room:
(a) Combustion air opening, with a minimum free area
of one square inch per 4000 Btu/hr input (5.5 cm² per
kW). This opening must be located within 12" (30 cm)
of the bottom of the enclosure.
(b) Ventilation air opening, with a minimum free area of
one square inch per 4000 Btu/hr input (5.5 cm² per kW).
This opening must be located within 12" (30 cm) of the
top of the enclosure.
2. COMBUSTION AIR THROUGH DUCTS
If combustion and ventilation air is taken from the outdoors using
a duct to deliver the air to the equipment room, each of the two
openings should be sized based on a minimum free area of one
square inch per 2000 Btu/hr (11 cm² per kW) of input.
The combustion air duct must be located within 12" (30 cm) of
the bottom of the enclosure and the ventilation duct must be
located must be located within 12" (30 cm) of the top of the
enclosure.
3. COMBUSTION AIR FROM INTERIOR SPACE
If air is taken from another interior space, each of
the two openings specified above should have a
net free area of one square inch for each 1000
Btu/hr (22 cm² per kW) of input, but not less than
100 square inches (645 cm²).
The combustion air opening must be located within
12" (30 cm) of the bottom of the enclosure and the
ventilation opening must be located must be
located within 12" (30 cm) of the top of the
enclosure