Installation of Two Pipe Venting – Vertical
Refer to the diagram below for venting on vertical concentric systems. The combustion air pipe must terminate at least 12 inches above the roof. This clearance may need to be increased to accommodate for snow accumulation. The exhaust must terminate at least 12 inches above and 12 inches horizontally from the combustion air inlet.
Exhaust Vent | C |
Combustion | |
Terminal | Air Inlet |
| Terminal |
B |
|
| A |
Roof Line |
|
EXHAUST | COMBUSTION AIR |
D |
|
| Tee with |
D | drip leg and |
A = 12 inch minimum, but should size according to expected snow depth
B = 24 inch minimum C = 12 inch minimum D = 12 inch minimum
Vent Connection Diameter
Vent terminals must be used. Construct the vent system as shown in the drawings and refer to the table for the correct vent connection diameters.
Furnace Size | Exhaust | Combustion |
(MBH) | (inches) | (inches) |
|
|
|
75 - 175 | 4 | 4 |
|
|
|
200 - 400 | 6 | 6 |
|
|
|
Vent Length
Refer to table for minimum and maximum vent lengths. The minimum vent length is 10 feet and the maximum vent length is 70 feet. The total equivalent vent length must include elbows. The equivalent length of a 4 inch elbow is 6 feet and the equivalent length of a 6 inch elbow is 10 feet.
Vent | Minimum | Maximum |
Length | (feet) | (feet) |
|
|
|
Vertical | 10 | 70 |
|
|
|
1. Install Exhaust Pipe
Run an exhaust pipe from the unit’s combustion exhaust through the roof to the outdoors. The exhaust pipe must terminate at least 12 inches above the outside surface of the roof. This clearance may need to be increased to accommodate snow accumulation. Attach the exhaust vent terminal to the end of the exhaust pipe.
2. Install Combustion Air Pipe
Run a combustion air pipe from the unit’s combustion air intake through the roof to the outdoors. The combustion air pipe must terminate at least 12 inches horizontally and vertically from the combustion exhaust pipe and at least 24 inches from the exterior surface of the roof. These clearances may need to be increased to accommodate for expected snow accumulation. Attach the combustion air terminal to the end of the combustion air pipe.
3. Seal Roof Penetration
Using an appropriate method, seal the roof openings around the vent pipes.
INTAKE END
Exhaust Connection | Exhaust Connection |
(Model IGX) | (Model IG) |
DISCHARGE
END
Combustion Air Connection | Combustion Air Connection |
(Model IGX) | (Model IG) |
14 Model IG / IGX
®
