Weil-McLain 550 MBH Nstallation And Operation Manual page 26

®
SlimFit Series 3
Direct Exhaust
Combustion air openings for direct
exhaust
air for direct exhaust boilers is provided from the
boiler room. Follow all instructions in the Boiler
manual plus all applicable codes, providing com-
bustion air openings as specified. Failure to comply
could result in severe personal injury, death or
substantial property damage.
1. Combustion air must be supplied through openings into the
boiler room, following the instructions in this manual and
compliant with all applicable codes. Read the warning in
Figure 12, page 22, 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 SlimFit 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
installed louvers or grilles
when sizing the air openings.
Special considerations
Tight construction
ANSI Z223.1 defines 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 . . .
26
COMMERCIAL CONDENSING GAS
Combustion and ventilation
after reduction for any
. Be sure to consider this reduction
—
-
FIRED WATER BOILER
3. Caulking or sealants are applied to areas such as joints around
windows and door frames, between sole plates and floors, 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
firing 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 fitted with motorized dampers, electrically
interlock the damper to:
Prevent the boiler from firing if the damper is not fully open.
Shut the boiler down should the damper close during boiler
operation.
The SlimFit control provides a Proof of Closure function which
will prevent the boiler from firing if the damper is not fully
open or closes during boiler operation. Please refer to the Boiler
Manual for installation and wiring instructions.
Every vent pipe requires a
the SlimFit boiler. Purchase separately from Weil-
McLain.
Boiler Manual
. Bird screens are not supplied with
Part number 550-100-168/0516