In cold climates, the use of type “B” double wall vent pipe or an insulated single wall pipe for combustion air is recommended to help prevent moisture in the cool incoming air from condensing and leaking from the inlet pipe.
Termination point for the flue products must follow the clearance requirements in the Vertical or Horizontal Vent Termination sections of the Category IV Venting.
CAUTION
Appliances that are shut down or will not operate may experience freezing due to convective airflow in the air inlet pipe connected to the appliance.
TABLE - F
Direct Vent and
and Air Inlet Pipe Sizes
|
|
| Air Inlet |
Input Btu/hr |
| Flue Size | Pipe Size |
|
|
|
|
1,500,000 |
| 6" | 6" |
________________ |
| ______________ | ________________ |
1,700,000 |
| 7" | 7"* |
________________ |
| _____________ | ________________ |
2,000,000 |
| 8" | 8" |
|
|
|
|
*Piping from the appliance to the air inlet cap may be either 7" or 8". An 8" diameter sidewall air inlet cap is provided in the vent kit.
Length of Air Inlet Pipe
The maximum total length of the sidewall or vertical roof top combustion air inlet pipe as installed from the appliance to the air inlet cap must not exceed 100 equivalent feet (30.5 m) in length. Subtract 5 feet (1.52 m) of equivalent length for each 90° elbow installed in the air inlet pipe system. Subtract 2 1/2 feet (0.7 m) of equivalent length for each 45° elbow installed in the air inlet pipe system.
Do not exceed limits for the combustion air inlet piping lengths.
Air Inlet Pipe Materials
The air inlet pipe(s) must be sealed. Choose acceptable combustion air inlet pipe materials from those specified in this section.
Select air inlet pipe material from the following specified materials:
•PVC, CPVC or ABS (6", 7"or 8" I.D.)*.
•Dryer Vent or Sealed Flexible Duct (not recommended for roof top air inlet).
•Galvanized steel vent pipe with joints and seams sealed as specified below.
•Type “B” double wall vent with joints and seams sealed as specified below.
* Plastic pipe may require an adapter (not provided) to transition between the air inlet connection on the appliance and the plastic air inlet pipe.
WARNING
Using vent or air intake materials other than those specified, failure to properly seal all seams and joints or failure to follow vent pipe manufacturer’s instructions can result in personal injury, death or property damage. Mixing of venting materials will void the warranty and certification of the appliance.
NOTE:
The use of double wall vent or insulated material for the combustion air inlet pipe is recommended in cold climates to prevent the condensation of airborne moisture in the incoming combustion air.
Sealing of Type “B” double wall vent material or galvanized vent pipe material used for air inlet pipe on a sidewall or vertical roof top Combustion Air Supply System.
a.Seal all joints and seams of the air inlet pipe using either Aluminum Foil Duct Tape meeting UL Standard 723 or
b.Do not install seams of vent pipe on the bottom of horizontal runs.
c.Secure all joints with a minimum of three sheet metal screws or pop rivets. Apply aluminum
foil duct tape or silicone sealant | to all | screws |
or rivets installed in the vent pipe. |
|
|
d. Ensure that the air inlet pipes | are | properly |
supported. |
|
|
The PVC, CPVC or ABS air inlet pipe should be cleaned and sealed with the pipe manufacturers recommended solvents and standard commercial pipe cement for the material used. The PVC, CPVC, ABS, Dryer Vent or Flex Duct air inlet pipe should use a silicone
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