Chimneys and Fireplace Sizing
Chimneys can be separated in two main categories:
- metal
- masonry
Prefab or Metal Chimneys
Prefab or metal chimneys, class A and double or triple walls are usually found in three diameters. Each diameter has a specific usable area, which is also called it's cross section.
The capacity of a chimney to remove smoke and/or energy (BTU's) from an appliance is directly related to the cross section area.
| Chimney Size | Common Venting Uses | |
|---|---|---|
| Inside diameter (inches) | Inside Area (square inches) | |
| 6 | 28.3 | Stoves, Central Heaters |
| 7 | 38.5 | Stoves, Central Heaters |
| 8 | 50.3 | Stoves, Small Fireplaces, Central Heaters |
| 10 | 78.6 | Stoves, Fireplaces, Central Heaters |
| 12 | 113 | Fireplaces, Central Heaters |
Masonry Flues
| Flue Size | Common Venting Uses | |
|---|---|---|
| Outside Diameter (inches) | Inside Area (square inches) | |
| 7 1/2 X 7 1/2 | 31 | Stoves, Central Heaters |
| 8 1/2 x 8 1/2 | 41 | Stoves, Central Heaters |
| 8 1/2 X 13 | 70 | Stoves, Fireplaces, Central Heaters |
| 13 X 13 | 99 | Fireplaces |
| 13 X 18 | 156 | Fireplaces |
Related Topics
• Combustion
Boiler house topics, fuels like oil, gas, coal, wood - chimneys, safety valves, tanks - combustion efficiency.
• Heating
Heating systems - capacity and design of boilers, pipelines, heat exchangers, expansion systems and more.
Related Documents
Chimney Sizing
Calculate chimney draft and required chimney area - online calculator.
Chimney's Explosion Doors
Recommended size of explosion doors or draught stabilizers in oil fired installations.
Chimney's Size vs. Boiler Power
The size of chimney vs. boiler's heat load.
Chimneys - Roof Termination
Chimneys and single wall vents roof termination.
Fuel Oil Burners
Pot types, gun types and rotary types fuel burners.
Natural Draft - Air Flow Volume and Velocity
Air flow - volume and velocity - due to stack or flue effect caused by indoor hot and outdoor cold temperature difference.