Part number 550-100-268/1220
4
CONDENSING
GAS
BOILER
—
V
ENT
A
DDENDUM
Direct Exhaust
(Category II Only) Boiler room air opening
Combustion air openings for direct exhaust
Provide combustion air openings to boiler
room and building.
Combustion and ventilation
air for direct exhaust boilers is provided from the
boiler room. Follow all instructions in the Boiler
manual and this addendum plus all applicable
codes, providing combustion air openings as speci-
fi ed. Failure to comply could result in severe per-
sonal injury, death or substantial property damage.
1. Combustion air must be supplied through openings into the
boiler room, following the instructions in this addendum
and compliant with all applicable codes. Read the warning in
Figure 1, page 5, and ensure the air and boiler room will not
contain contaminated air.
2. Where the boiler shares a space with other appliances, the
combustion air openings must be sized to handle the com-
bined requirements of all appliances in the space.
Sizing combustion air openings
Air openings provide for ventilation (as well as combustion air)
to prevent overheating of the boiler controls and boiler space.
Air is also needed for other appliances located in the same space.
Use Figure 2, page 6, selecting the appropriate installation condi-
tions.
Air openings must be sized to handle all appliances
and air movers (exhaust fans, etc.) using the air
supply.
The sizing given in Figure 2, page 6, is based on the National
Fuel Gas Code, ANSI Z223.1, allowing adequate air openings for
gravity-vented gas appliances (Category I) in addition to that
needed for the
Evergreen
boiler.
The air openings recommended in Figure 2, page 6, will allow
adequate ventilation and combustion air provided the boiler room
is not subjected to negative pressure due to exhaust fans or other
mechanical ventilation devices.
Refer to the National Fuel Gas Code for dealing with other con-
ditions.
Free area — louver allowance
The free area of openings means the area
after reduction for any
installed louvers or grilles
.
Be sure to consider this reduction when
sizing the air openings.
Special considerations
Tight construction
ANSI Z223.1 defi nes unusually tight construction where:
1. Walls and ceilings exposed to the outside atmosphere have a
continuous water vapor retarder with a rating of 1 perm or
less with openings gasketed, and . . .
2. Weather-stripping has been added on openable windows and
doors, and . . .
Every vent pipe requires a
bird screen at its
termination
. Bird screens are not supplied with
the
Evergreen
boiler. Purchase separately from
Weil-McLain.
3. Caulking or sealants are applied to areas such as joints around
windows and door frames, between sole plates and fl oors, be-
tween wall-ceiling joints, between wall panels, at penetrations
for plumbing, electrical, and gas lines, and in other openings.
For buildings with such construction, provide air openings into
the building from outside, sized per the appropriate case in Fig-
ure 2, page 6, if appliances are to use inside air for combustion
and ventilation.
Exhaust fans and air movers
The appliance space must never be under a negative pressure
unless all appliances are installed as direct vent. Always provide
air openings sized not only to the dimensions required for the
fi ring rate of all appliances, but also to handle the air movement
rate of the exhaust fans or air movers using air from the build-
ing or space.
Motorized air dampers
If the air openings are fi tted with motorized dampers, electrically
interlock the damper to:
• Prevent the boiler from fi ring if the damper is not fully open.
• Shut the boiler down should the damper close during boiler
operation.
The Evergreen control provides a Proof of Closure function
which will prevent the boiler from fi ring if the damper is not fully
open or closes during boiler operation. Please refer to the Boiler
Manual for installation and wiring instructions.
Ensure that the combustion air will not contain
