Intake Air Connection; Intake Air Screen - A.O. Smith BTH-120 Instruction Manual

11. If installing 3 inch vent pipe connect the vent pipe to the
exhaust elbow on the water heater.
12. If installing 4 inch vent pipe transition to 3 inch pipe at the
exhaust elbow on the water heater as shown in Figure 18 on
page 25. The field installed 3" pipe between the exhaust elbow
and the 4" x 3" reducer coupling should be 18 inches (45 cm)
or less in length.
13. Ensure the Intake Air Screen on the Intake Air Connection to
the water heater is removed before connecting the intake air
pipe to the water heater. See Figure 19.
Breathing Hazard - Carbon Monoxide Gas
Do not obstruct water heater air intake.
Gas and carbon monoxide detectors
are available.
Install water heater in accordance with
the instruction manual.
Breathing carbon monoxide can cause brain damage or
death. Always read and understand instruction manual.
note: Do not leave the screen inside the Intake Air
Connection for Direct Vent installations. Once the intake
air pipe is installed the screen will be hidden from view and
may become clogged with debris over time. This will cause
improper combustion and may also lead to Blocked Intake
Air fault conditions and associated control system lock outs.
120,000 & 150,000
Btu/hr MODELS

INTAKE AIR SCREEN

3 INCH INTAKE AIR CONNECTIONS
FACTORY INSTALLED
INTAKE AIR SCREEN
(remove for Direct Vent)
199,000 & 250,000
Btu/hr MODELS
figure 19
14. If installing 3 inch intake air pipe connect the intake air pipe to
the intake air connection on the water heater.
15. If installing 4 inch intake air pipe transition to 3 inch pipe at
the intake air connection on the water heater as shown in
Figure 20. The field installed 3" pipe between the intake air
connection and the 4" x 3" reducer coupling should be 18
inches (45 cm) or less in length.
4" PIPE FIELD 3" PIPE FIELD
SUPPLIED SUPPLIED
INTAKE AIR
4" x 3" REDUCER 3" COUPLING OR TEE
FIELD SUPPLIED FACTORY INSTALLED

INTAKE AIR CONNECTION

INTAKE AIR CONNECTION
INSTALL TEE FITTING AS CLOSE TO WATER HEATER
INTAKE AIR CONNECTION AS POSSIBLE
INTAKE AIR CONDENSATE TEE INSTALLATION
26
3" PIPE FACTORY
INSTALLED
COMBUSTION
BLOWER
figure 20
INTAKE
AIR
FACTORY
PIPING
INTAKE AIR
CONNECTION
FIELD SUPPLIED
3" x 3" x 1/2" TEE
WITH HOSE BARB
FITTING INSTALLED
CONNECT FIELD
SUPPLIED FLEXIBLE
DRAIN HOSE TO BARB
FITTING AND FORM A
LOOP WATER TRAP IN
DRAIN HOSE
RUN DRAIN HOSE
TO SUITABLE FLOOR
DRAIN SEPARATELY
FROM OTHER
CONDENSATE DRAINS
figure 21