Install Instructions
Part Number 550-142-902/1016
CGi
GAS-FIRED WATER BOILER — SERIES 3 — Boiler Manual
11
Prepare boiler location — air openings
1e
Unusually tight construction
Unusuallytightconstructionmeans(perANSIZ223.1/
NFPA54)buildingsinwhich:
a. Walls and ceilings exposed to the outside atmo-
sphere 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 toareassuchas
joints around windows and door frames, between
sole plates and floors, between wall-ceiling joints,
between wall panels, at penetrations for plumbing,
electrical, and gas lines, and in other openings.
For such construction cases, if appliances use inside air
for combustion, provide air openings into the building
from outside
.Sizeandlocatetheseopeningsperthe
appropriate case in Figure 3, 4 or 5 on page 10.
Motorized air dampers
If the air openings are fitted with motorized dampers,
electrically interlock the damper to:
• Preventtheboilerfromringifthedamperisnot
fully open.
• Shuttheboilerdownshouldthedamperclosedur-
ing boiler operation.
To accomplish this interlock, wire an
isolated contact
(proving the damper open) in series with the thermo-
stat input to the boiler. The boiler will not start if this
contact is open, and will shut down should it open
during operation.
Exhaust fans and air movers
The appliance space must never be under a negative
pressure, even if the appliance(s) are installed as di-
rectvent.Alwaysprovideairopeningssizednotonly
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.
Single air opening option
✷
Asinglecombustionairopeningcanbeusedinlieuofthetwo‑opening
options on page 10, provided:
Clearances from boiler to walls
• TheboilermusthaveclearancesofatleastthoseshowninFigure1a,
page 7.
Opening must be directly to outside
• Theopeningmustconnectdirectlytotheoutdoorsortoaspacethat
communicates directly to the outdoors (not to an interior space).
• Theaircanbeprovidedthroughadirectopeningorthroughahorizontal
or vertical duct.
Opening placement
• Thetopoftheairopeningmustbewithin12inchesoftheceiling.
Opening size
• Thefreeareaoftheopeningmustbeatleastequaltothesumofthe
areas of all equipment vent connectors in the space, and . . .
• Thefreeareaoftheopeningmustbeatleast1squareinchper3,000
Btu/hrinputratingofallequipmentlocatedinthespace.
FREE AREA of openings — the minimum areas
given in this manual are free area (equals the area,
length times width of opening, after deduction for
louver obstruction).
Use the free area information provided by the louver manufacturer.
When this information is not available, assume:
• Woodlouvers—assumefreeareais20%oftotal;sotheactualarea
of each opening with wood louvers would be 5 times the required
free area.
• Metallouvers—assumefreeareais60%ofactualarea;so,forwood
louvers, the actual area of each opening must be 1.67 times the re-
quired free area.
Exception for large spaces
✷
Nocombustionairopeningsareneededwhentheboiler(andotherap-
pliances) are installed in a space with a volume at least 50 cubic feet per
1,000 Btuh
of all installed appliances, provided:
• the building must not have unusually tight construction
(see definition, this page).
• allclearancesaroundtheboilermustbenolessthanshowninFigure1a,
page 7.
To determine if the space is large enough to qualify:
• AddthetotalinputofallappliancesinMBH(1,000’sofBtuh).
• Multiplythisnumbertimes50todetermineminimumroomvolume.
• Example:Foratotalinputof100MBH(100,000Btuh),minimum
volumeis50x100=5,000cubicfeet.Ataceilingheightof8feet,the
space must have at least 5,000 ÷ 8 = 625 square feet (25 feet x 25 feet,
for instance).