Installation & Service Manual
2 Venting (continued)
Figure
Figure
CAUTION
Units which are shut down or will not operate may experience freezing due to convective air flow in flue pipe, through the air inlet, or from negative pressure in the equipment room. In cold climates, operate pump continuously to help prevent freezing of boiler water. Provide proper freeze protection. See Freeze Protection, page 46.
TABLE 2A
FLUE PIPE SIZES
MODEL | FLUE SIZE | MODEL | FLUE SIZE |
|
|
|
|
497 | 6'' | 1257 | 12'' |
647 | 8'' | 1437 | 12'' |
747 | 8'' | 1797 | 14'' |
987 | 10'' | 2067 | 14'' |
Installer may increase diameter one pipe size for ease of installation, if needed.
Vent system options
Vent System Options
This unit has two venting options.
1.Conventional Negative Draft Venting
This option uses a vertical rooftop flue termination.
Combustion air is supplied from the mechanical room. See page 15 for detailed information.
2.Outdoor Installation Venting
This option uses the installation of special air inlet and vent caps on the unit.
All units are shipped from the factory equipped for conventional negative draft venting. All other optional vent systems require the installation of specific vent kits and venting materials. The following is a detailed explanation of the installation requirements for each venting system, components used and part numbers of vent kits for each model.
Barometric damper location
Any venting system option that requires a barometric damper must adhere to the following directions for optimum performance. The preferred location for the barometric damper is in a tee or collar installed in the vertical pipe rising from the unit’s flue outlet. The barometric damper MUST NOT be installed in a bull head tee installed on the unit’s flue outlet. The tee or collar containing the barometric damper should be approximately three feet vertically above the connection to the unit’s flue outlet. This location ensures that any positive velocity pressure from the unit’s internal combustion fan is dissipated and the flue products are rising due to buoyancy generated from the temperature of the flue products. Adjust the weights on the damper to ensure that draft is maintained within the specified ranges.
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