Weil-McLain SVF 1500 Manual page 32

SVF
™
Series 1
Commercial Condensing Gas-Fired Water Boiler — Boiler Manual
DIRECT EXHAUST — Boiler room air openings
Combustion air provision
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The SVF
Commercial boiler can use inside air if no contaminants are
present in the boiler space. (If contaminants are likely to be present,
install the boiler as a direct vent appliance, using the appropriate vent
instructions in this manual.)
The boiler room must be fitted with combustion air openings large
enough to provide air for all appliances in the room. Use the following
information to size the openings. Ensure the installation complies with
all applicable codes and standards.
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 26, page 33, 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 26, page 33 is based on the National Fuel
Gas Code - ANSI Z223.1/NFPA 54 – latest edition, allowing adequate
air openings for gravity-vented gas appliances (Category I) in addition
TM
to that needed for the SVF
boiler.
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The SVF
Commercial boiler is rated Category IV (pressurized
vent), and has varying requirements for combustion and ventilation
air, reflected by the special sizing instructions given in this manual.
The air openings recommended in Figure 26, page 33 will allow ad-
equate 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 - ANSI Z223.1/NFPA 54 – latest
edition for dealing with other conditions.
Free area — louver allowance
The free area of openings means the area
. Be sure to consider this reduction when
installed louvers or grilles
sizing the air opening.
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after reduction for any
Special considerations
Tight construction
National Fuel Gas Code - ANSI Z223.1/NFPA 54 – latest edition
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 . . .
3. Caulking or sealants are applied to areas such as joints around
windows and door frames, between sole plates and floors, between
wall-ceiling joints, between wall panels, at penetrations for plumb-
ing, 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 Figure 26,
page 33 if appliances are to use inside air for combustion and ventila-
tion.
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 ap-
pliances, but also to handle the air movement rate of the exhaust fans
or air movers using air from the building or space.
The Damper/Louver control can also provide 120V to operate a
damper, (see Aux. pump system) as well as provide input for a closure
switch to allow the damper to prove the damper is in open position.
Part number 550-100-250/0819