Locating the New Water Heater (cont’d)
9″ min. from any overhang
C
Lof Flue
12″ min.
Figure 2
Must maintain adequate service and maintenance accessibility. 
Range of degrees
Figure 4available for vent pipe installation.
Venting Through Roof – Clearances
• 0″ clearance for 3″ (or optional 2″ and 4″) PVC, ABS, or CPVC |
Schedule 40 piping from combustible surfaces. |
• The Power Vent outlet terminal shall terminate at least 18 inch- |
es above the roof surface. Figure 5. |
• The location selection must provide clearances for servicing |
and proper operation of the water heater. Figure 4. |
• The venting system must be installed in a manner which |
allows inspection of the installation of the venting pipes and |
joints as well as periodic inspection after installation as |
required by ANSI Standards. |
48″ min.
48″ min.
POWER VENT TERMINAL 12″ min.
Figure 3a
|
| VENT |
|
|
|
|
| IF “B” DIMENSION | |
| TERMINAL |
| ||
|
|
| ||
| POWER | B |
| IS LESS THAN 10’ |
|
|
| ||
| . |
|
|
|
min | 36″ min. | |||
″ |
| |||
12 |
|
|
|
|
|
| FORCED AIR | ||
|
| INLET INTO | ||
| GRADE |
| BLDG. | |
|
|
|
| |
45° VENT CAP |
| 90° STREET ELL |
W/SCREEN |
|
|
|
| |
|
|
|
18″
VENT TERMINAL
Figure 3b
18″ MIN.
18″ MIN.
18″ TO WALL OR OTHER OBSTRUCTIONS THAT MAY INTERFERE WITH VENTING.
VENT TERMINAL
CORNER OF BUILDING
Figure 5
Combustion Air and Ventilation for Appliances Located in Unconfined Spaces
POWER VENT TERMINAL
18″
NATURAL DRAFT (GRAVITY),
DIRECT VENT, POWER VENT
OR POWER DIRECT VENT
24″APPLIANCE INLET AND/OR OUTLET VENT(S)
45°
Figure 3c
Unconfined Space is a space whose volume is not less than 50 cubic feet per 1,000 Btu per hour of the aggregate input rating of all appliances installed in that space. Rooms communicating directly with the space in which the appliances are installed, through openings not furnished with doors, are considered a part of the unconfined space.
In unconfined spaces in buildings, infiltration may be adequate to provide air for combustion, ventilation and dilution of flue gases. However, in buildings of tight construction (for example, weather stripping, heavily insulated, caulked, vapor barrier, etc.), additional air may need to be provided using the methods described in Combustion Air and Ventilation for Appliances Located in Confined Spaces.
9
