31
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.
The Stainless Steel direct vent cap must be fur-
nished by the boiler manufacturer in accordance
with its listing.
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.
Fig. 23: Horizontal Thru-Wall Direct
Venting/Combustion Air
(Category III)
Summary of Contents for 751
Page 2: ...2...
Page 6: ...6 Component Locations Fig 1 Component Locations...
Page 15: ...15 Fig 6 Dual Boiler Piping Fig 7 Dual Boiler Piping with CHX...
Page 20: ...20 Fig 13 Single Boiler Pool Application Fig 14 Single Boiler Pool Application with CHX...
