Condensate Drains - Carrier Aero 39MN Series Installation, Start-Up And Service Instructions Manual

available to the heater, poor combustion and inefficient opera-
tion will result.
For outdoor installations, the heating unit cabinet combus-
tion air openings should be sized to provide 1 sq in. of free area
per 4000 Btuh of input. Combustion air inlet and flue gas outlet
must be located in the same pressure zone to minimize effects
of wind on burner and heater performance.
For indoor installations, locate heating unit to ensure an ade-
quate supply of fresh air to replace air used in the combustion
and ventilation process. Install air openings that provide a total
free area in accordance with the National Fuel Gas Code (AN-
SI Z223.1 or NFPA 54) in the United States or CAN/CGA B-
149 Installation Code in Canada.
Do not install unit in a confined space (a space whose vol-
ume is less than 50 cubic feet per 1000 Btuh of furnace input
rating) without providing wall openings leading to and from
the space. Provide openings near floor and ceiling to provide
air for combustion and ventilation. Size openings for total Btuh
TWO-STAGE
GAS VALVE
3/4" NPT GAS
INLET
CONNECTION
DRAFT INDUCER
ASSEMBLY
DRAFT INDUCER
MOTOR
MOTOR SUPPORT
BRACKET
WIRE HARNESS
TO JB/IGNITION
CONTROL
MODULATOR VALVE
(MODULATING SYSTEMS ONLY)
CONDENSATE DRAIN
FITTING
Fig. 136 — Gas-Fired Duct Furnace Components
of all appliances in confined space and provide openings as fol-
lows:
• Air from inside building — openings 1 sq in. free area
per 1000 Btuh, but never less than 100 sq in.
• Air from outside through a duct — openings 1 sq in. free
area per 2000 Btuh
• Air direct from outside — openings 1 sq in. free area per
4000 Btuh
VENTING — Safe operation of indirect-fired gas furnaces
requires a properly operating venting system that vents all the
products of combustion (flue gases) to the outside atmosphere.
Failure to provide proper venting affects furnace perfor-
mance and may result in a health hazard which could
cause serious personal injury or death.
AIR PRESSURE
164
WARNING
SWITCH
FLAME ROLLOUT
SWITCH
FLAME SENSOR
HI LIMIT SWITCH
MANIFOLD
PRESSURE TAP
SPARK IGNITER
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