escape through such appliances or vents. Do not vent the furnace to a fireplace chimney or building chase.
If removing an existing furnace in a venting system, the venting system may not be properly sized. To test the vent system with the remaining appliances, follow the test outlined below.
The following steps shall be followed with each appliance connected to the venting system placed in operation, while any other appliances connected to the venting system are not in operation:
Vent Pipe Material
Vent and combustion air pipe and fittings must be one of the following materials and must conform to the indicated ANSI/ASTM standards:
Material | Standard |
Schedule 40 PVC | D1785 |
D2665 | |
D2241 | |
& |
|
D2661 | |
Schedule 40 ABS | F628 |
Foam/Cellular Core PVC | F891 |
Cement and primer must conform to ATSM Standard D2564 for PVC and Standard D2235 for ABS. When joining PVC piping to ABS, use an appropriate solvent cement and procedure per the piping manufacturer's recommendation and ASTM Standard D3138.
Vent Pipe Installation
Pipe Routing and Support
Route piping as directly as possible between the furnace and the outdoors and remember that routing affects pipe length limitations per Table 6. Locate the combustion air intake and the vent exhaust in the same atmospheric pressure zone - i.e. both must exit the building though the same portion of exterior wall or roof. Vent piping must be sloped upwards not less than 1/4" per foot in the direction from the furnace to the terminal. This is to ensure that any condensate flows back to the furnace where it can be disposed of through the condensate disposal system.
!CAUTION:
Combustion air must not be drawn from occupied spaces and a corrosive atmosphere.
The quality of outdoor air must also be considered. Be sure that the combustion air intake is not located near a source of solvent fumes or other chemicals which can cause corrosion of the furnace combustion system.
Piping must be mechanically supported so that its weight does not bear down on the furnace. Supports must be at intervals no greater than five feet, and at smaller intervals if necessary to ensure that there are no sagging sections to trap water (See Figures 16 & 17).
These condensing furnaces have been certified for installation with zero clearance between vent piping and combustible surfaces. However, it is good practice to allow space for convenience in installation and service.
Location of Outdoor Terminations
Vent and combustion air intake terminations must be located to ensure proper furnace operation and to conform to applicable codes. Figure 15 illustrates necessary distances from the vent termination to windows and building air intakes. In Canada, the Canadian Fuel
Gas Code takes precedence over these instructions. Specifically, all minimum distance requirements with respect to termination of the vent piping listed below.
The following list is a summary of vent terminal location requirements:
1.The termination must be 12 inches above snow level or grade level whichever is higher. See Figure 18 for alternate method to achieve 12" above snow level.
2.The minimum distance for a direct vent
3.The vent termination shall be a minimum of 3 ft. above any forced air inlet within 10 ft.
4.The vent termination shall be located at least 4 ft. horizontally from any electric meter, gas meter, regulator and any relief equipment. These distances apply ONLY to U.S. installations. In Canada, the Cana- dian Fuel Gas Code takes precedence.
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