Raypak 751 manual Horizontal Thru-wallDirect Vent Termination

Horizontal Thru-wall Direct Venting System (Category III) Installation

These installations utilize the boiler-mounted blower to vent the combustion products to the outdoors. Combustion air is taken from inside the room and the vent is installed horizontally through the wall to the out- doors. Adequate combustion and ventilation air must be supplied to the boiler room in accordance with the National Fuel Gas Code or, in Canada, the latest edi- tion of CSA B149 Installation Code for Gas Burning Appliances and Equipment.

The total length of the thru-wall exhaust vent system cannot exceed sixty-five (65) feet in length for the flue outlet. Each elbow used is equal to ten (10) feet of straight pipe. This will allow installation in one of the four following combinations:

·65′ of straight flue pipe.

·55′ of straight flue pipe and one elbow.

·45′ of straight flue pipe and two elbows.

·35′ of straight pipe and three elbows.

The direct vent cap is not considered in the overall length of the venting system. The vent must be installed to prevent the flue gas leakage. Care must be taken during assembly to ensure that all joints are sealed properly and are airtight.

The vent must be installed to prevent the potential accumulation of condensate in the vent pipes. It is rec- ommended that:

a)The vent be installed with a slight downward slope of not more than 1/4" per foot of horizontal run to the vent terminal.

b)The vent be insulated through the length of the horizontal run.

For appliances installed in extreme cold climate, it is recommended that:

a)The vent be installed with a slight upward slope of not more than 1/4" per foot of horizontal run to the vent terminal. In this case, an approved conden- sate trap must be installed per applicable codes.

b)The vent be insulated through the length of the horizontal run.

Horizontal Thru-wall Direct Vent Termination

The direct vent cap MUST be mounted on the exterior of the building. The direct vent cap cannot be installed in a well or below grade. The direct vent cap must be installed at least one (1) foot above ground level and above normal snow levels. The Raypak supplied direct vent cap must be used.

WARNING: No substitutions of flue pipe or vent cap material are allowed. Such substitutions would jeopardize the safety and health of inhabitants.

WARNING: For common vent installations, contact the factory.

The Stainless Steel direct vent cap must be fur- nished by the boiler manufacturer in accordance with its listing.

Fig. 23: Horizontal Thru-Wall Direct

Venting/Combustion Air

(Category III)

31