Fresh Air
8
Combustion Air Supply (Continued)
Combustion air opening (oil-fired installations)
Install a combustion air opening. Ensure that all code requirements are met.
Minimum round duct diameters are as follows:
Boiler Model
Model No. VB2-18 VB2-22 VB2-33 VB2-40 VB2-50 VB2-63
Round duct for combustion air supply
*
Ø” 5 5 6 7 8 8
*
These figures are based on a
minimum equivalent duct length of
20 ft/6 m. For equivalent duct lengths
in excess of 20 ft/6 m, up to and
including 50 ft/15 m, increase round
duct diameter by one size.
General
The heating contractor shall ensure all
of the following requirements are met:
H An adequate supply of combustion air
must be available to ensure proper
combustion.
H Ambient air temperatures must be
maintained within safe operating
limits.
H When a damper is provided in any
opening intended to admit combustion
air into the room within which the
appliance is installed, the damper shall
be interlocked to prevent any burner
from s tarting before the damper is
fully open.
H Each duct used to convey air from the
outdoors shall have:
1. A cross-sectional area throughout
its length at least equal to the free
area of the inlet and outlet
openings which it connects,
2. A minimum dimension of
3” / 76 mm at any cross-section,
3. When making provision for outside
combustion air, the intake shall not
be less than 1 ft / 0.3 m above the
anticipated snow level for the
location.
H The heating contractor must check
with local authorities (municipal
building department, gas utility) for
combustion air requirements particular
to the area.
5167 404 v1.9
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