Raypak 122-322 Vertical Direct Vent System Installation, Vertical Direct Vent Termination

•Vertical Direct Vent System Installation

These installations utilize the heater mounted blower to draw combustion air from outdoors and uses the natural buoyancy of the heated flue products to create a thermal driving head that expels the exhaust gases from the flue. The negative draft must be within the range of -0.01” to -0.08” W.C. as measured 12 in. from the appliance outlet to insure proper operation. The vent material must be in accordance with the above instructions for vent materials. Vent material must be listed by a nationally recognized test agency.

The maximum and minimum venting length for Category I appliance shall be determined per the latest edition of the NFGC (U.S.) and B149.1 and .2 Installation Code (Canada).

The connection from the appliance exhaust vent to the stack must be as direct as possible and should be the same as or larger than the vent outlet. The vent must be installed to prevent accumulation of condensate and, where necessary, have means provided for drainage of condensate. The horizontal breaching of a vent must have an upward slope of not less than 1/4 inch per linear foot from the heater to the vent terminal. The horizontal portions of the vent shall also be supported for the design and weight of the material employed to maintain clearances and to prevent physical damage or separation of joints.

•Vertical Direct Vent Termination

The exhaust vent terminal should be vertical and should terminate outside the building at least two (2) feet above the highest point of the roof within 10 feet. The vent cap should have a minimum clearance of four (4) feet horizontally from and in no case above or below (unless a four (4) foot horizontal distance is maintained) electric meters, gas meters, regulators and relief equipment. The distance of the vent terminal from adjacent public walkways, adjacent buildings, open windows and building openings must be consistent with the NFGC, or in Canada, the B149.1 and .2. Installation Code. Gas vents supported only by flashing and extended above the roof more than five feet should be securely guyed or braced to withstand snow and wind loads.

The vertical direct vent cap is designed for roof top mounting only. The air inlet opening MUST be installed one (1) foot above the roof line or above normal snow levels that might obstruct combustion air flow. This dimension is critical to the correct operation of the heater and venting system and reduces the chance of blockage from snow. The vent cap must have a minimum 3 foot clearance from the air inlet opening.

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