A.O. Smith BTH 120-250(A) - Manual (Page 8)

8
TRANSMITTED INTO THE LIVING SPACES.
IMPORTANT
The vent system must terminate so that proper clearances are maintained
as cited in local codes or the latest edition of the National Fuel Gas Code,
ANSI Z223.1/NFPA 54 and for Canadian installations consult the Canadian
Installation Codes and CAN/CGA B149.1 and .2.
1. Do not terminate the exhaust vent terminal over public area where
condensate or vapor can cause nuisance or hazard.
2. For direct vent, the venting system shall terminate at least 1' (30.5 cm)
below, 1' (30.5 cm) horizontally from or 1' (30.5 cm) above any door,
window, or gravity air inlet into building.
3. For horizontal the venting system, using room for combustion, the vent
terminal shall terminate 4' (122 cm) below, 4' (122 cm) horizontally from
or 1' (30.5 cm) above any door, window, or gravity air inlet into building.
4. The manufacturer also recommends the vent system terminations not
be installed closer than 3' (91cm) from an inside corner of an L shaped
structure. And not less than 1' (30.5 cm) above grade or anticipated
snow level.
5. The vent termination shall not be mounted directly above or within 3'
(91cm) horizontally from an oil tank vent or gas meter to avoid potential
freeze-up from condensation.
6. The vent shall terminate a minimum of 12" (30.5 cm) above expected
snowfall level to prevent blockage of vent termination.
Plan the vent system layout so that proper clearances are maintained from
plumbing and wiring.
Vent pipes serving power vented appliances are classified by building
codes as "vent connectors". Required clearances from combustible
materials must be provided in accordance with information in this manual
under LOCATION OF HEATER and CLEARANCES, and with National Fuel
Gas Code and local Codes.
IMPORTANT
Plan the layout of the vent system backwards from the vent termination to
the appliance.
WARNING
USE ONLY THE VENT TERMINALS SUPPLIED WITH THIS UNIT.
TERMINATION OF A VENT SYSTEM WITH A DEVICE OTHER THAN THE
SUPPLIED VENT TERMINATIONS WILL AFFECT SYSTEM
PERFORMANCE AND RESULT IN A SAFETY HAZARD.
DIRECT VENTING
The air intake provided on the unit contains a mesh screen (see Figure 7)
to prevent large particles from entering the unit.
FIGURE 7
WARNING
WHEN THE UNIT IS TO BE SETUP AS A DIRECT VENT, THE MESH SCREEN
MUST BE REMOVED. THE INLET VENT PIPE MAY THEN BE GLUED TO
THE AIR INTAKE (see Figure 8) PROVIDED ON THE UNIT.
FIGURE 8
DIRECT VENT TERMINAL INSTALLATION
IMPORTANT
THIS UNIT CONSISTS OF TWO VENT TERMINALS - AN INTAKE VENT
TERMINAL AND AN EXHAUST VENT TERMINAL. THE INTAKE VENT
TERMINAL IS A 3" 45° PVC ELBOW (OR 3" PVC TEE FOR BTH 250) WITH A
MESH WIRE SCREEN AND THE EXHAUST VENT TERMINAL IS A 3" 45°PVC
ELBOW WITH A MESH WIRE SCREEN.
NOTE: TO PREVENT EXHAUSTING PRODUCTS FROM CIRCULATING TO
THE AIR INTAKE IN WINDY/COLD AREAS, THE MAXIMUM PRACTICAL
DISTANCE BETWEEN THESE TWO TERMINALS IS RECOMMENDED.
3" (7.6cm) 45° PVC ELBOW WITH MESH SCREEN
BTH 120
BTH 150
& 199
BTH 250