Weil-McLain GOLD CGt Manual page 11

GOLD CGt Gas-Fired Water Boiler — Boiler Manual
4. When combustion air is supplied to the boiler
space
directly from outside through horizontal
: Provide two permanent openings:
ducts (Figure 6)
• One air opening within 12 inches of floor.
• A second opening within 12 inches of ceiling.
Each opening must provide a minimum free area
of
1 square inch per 1,000 Btuh of input
appliances in room plus requirements for any
exhaust fans in room. The duct cross sectional area
must be no less than the required area of the
permanent openings.
Figure 5 Air from outdoors — vertical ducts
Outside or ventilated attic
Each opening free area =
1 sq. inch per 1,000 Btuh
CGt
boiler
Other
appliances
Ventilated
crawl space
029003
Figure 6 Air from outdoors — horizontal
ducts
Each opening free area =
1 sq. inch per 1,000 Btuh
CGt
boiler
Other
appliances
029004
Part Number 550-110-290/0501
Exception to combustion air opening
rules:
NO
appliances) are installed in a space with a volume
feet per 1,000 Btuh of all installed appliances. Sum the total input of all
appliances in MBH (1,000's of Btuh) and multiply this number times 50.
Building must not be of Tight construction
of all
Example:
Special considerations
Tight construction
ANSI Z223.1 defines unusually tight construction where:
a. 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 . . .
b. Weather-stripping has been added on openable windows and doors,
and . . .
c. 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 plumbing, electrical,
— or —
12"
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
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, even if the
appliance(s) are installed as direct vent. Always provide air openings sized
0 to 12"
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 building 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.
0 to 12"
To accomplish this interlock, wire an
open) in series with the thermostat input to the boiler. The boiler will not
start if this contact is open, and will shut down should it open during
operation.
combustion air openings are needed when the boiler (and other
For total input of 100 MBH (1000,000 Btuh), minimum
volume is 50 x 100 = 5,000 cubic feet. At a ceiling height of
8 feet, space must have at least 5,000 ÷ 8 = 625 square feet (25
feet x 25 feet, for instance).
than 50 cubic
NO LESS
(see below).
Figures 4 or 5
(proving the damper
isolated contact
if
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