
Flue Terminal Clearances (ANS Z21.10.3 ● CSA 4.3)
D
E
 B
 B
L
INSIDE
CORNER DETAIL
G
H
A
| 
 | 
 | I | M | |
| 
 | 
 | B | 
 | |
| 
 | B | FIXED | K | |
| 
 | CLOSED | |||
| 
 | 
 | |||
| 
 | OPERABLE | 
 | ||
| C | B | J | 
 | |
| 
 | 
 | |||
| FIXED | B | X AIR SUPPLY INLET | ||
| CLOSED | ||||
| A | ||||
| OPERABLE | ||||
| 
 | 
 | 
 | ||
V VENT TERMINAL
F
AREA WHERE
B  TERMINAL IS NOT PERMITTTED
TERMINAL IS NOT PERMITTTED
| Ref | Description | US Installations | |
| 
 | 
 | 
 | |
| A | Clearance above grade, veranda, porch, deck, or balcony | 12 inches (30 cm) | |
| 
 | 
 | 
 | |
| B | Clearance to window or door that may be opened | 12 inches (30 cm) | |
| 
 | 
 | 
 | |
| C | Clearance to permanently closed window | * | |
| 
 | 
 | 
 | |
| 
 | Vertical clearance to ventilated soffit, located above the terminal | 
 | |
| D | within a horizontal distance of 2 feet (61 cm) from the center line | * | |
| 
 | of the terminal | 
 | |
| 
 | 
 | 
 | |
| E | Clearance to unventilated soffit | * | |
| 
 | 
 | 
 | |
| F | Clearance to outside corner | * | |
| 
 | 
 | 
 | |
| G | Clearance to inside corner | * | |
| 
 | 
 | 
 | |
| H | Clearance to each side of center line extended above meter/ | * | |
| regulator assembly | |||
| 
 | 
 | ||
| 
 | 
 | 
 | |
| I | Clearance to service regulator vent outlet | * | |
| 
 | 
 | 
 | |
| J | Clearance to nonmechanical air supply inlet to building or the | 12 inches (30 cm) | |
| combustion air inlet to any other appliance | |||
| 
 | 
 | ||
| 
 | 
 | 
 | |
| K | Clearance to a mechanical air supply inlet | 3 feet (91 cm) above if within | |
| 10 feet (3 m) horizontally | |||
| 
 | 
 | ||
| 
 | 
 | 
 | |
| L | Clearance above paved sidewalk or paved driveway located on | * | |
| public property | |||
| 
 | 
 | ||
| 
 | 
 | 
 | |
| M | Clearance under veranda, porch, deck, or balcony | * | |
| 
 | 
 | 
 | 
1A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.
2Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor.
∗For clearances not specified in ANSI Z223.1/NFPA 54 or CSA B149.1, clearances are in accordance with local installation codes and the requirements of the gas supplier.
| 305, 505, 705 Indoor Manual | 25 |