Page 11
Vent Piping Guidelines
G61MPVT furnaces, with the exception of the
G61MPVT−60D−135, can be installed as either a Non−Di-
rect Vent or a Direct Vent gas central furnace. The
G61MPVT−60D−135 can only be installed as a Direct
Vent (two pipe) gas central furnace.
NOTE − In Non-Direct Vent installations, combustion air is
taken from indoors and flue gases are discharged outdoors.
In Direct Vent installations, combustion air is taken from out-
doors and flue gases are discharged outdoors.
Intake and exhaust pipe sizing in Direct Vent applications
and exhaust pipe sizing in Non-Direct Vent applications −−
Size pipe according to tables 5 and 6. Table 5 lists the mini-
mum equivalent vent pipe lengths permitted. Table 6 lists
the maximum equivalent pipe lengths permitted.
Maximum vent length is defined as:
Total length (linear meters) of pipe,
Plus Equivalent length (meters) of fittings,
Plus Equivalent length (meters) of termination.
NOTE − Include ALL pipe and ALL fittings, both in
doors and outdoors.
Regardless of the diameter of pipe used, the standard roof
and wall terminations described in section Exhaust Piping
Terminations should be used. Exhaust vent termination
pipe is sized to optimize the velocity of the exhaust gas as
it exits the termination. Refer to table 7.
NOTE − The exhaust pipe should be offset a minimum of
305mm (12 inches) to avoid the possibility of water droplets
being released from the exhaust termination. The mini-
mum exhaust vent length is 4.5m (15 feet). Shorter exhaust
vent lengths may result in the discharge of water droplets
from the exhaust termination, in spite of the 305mm
(12−inch) vertical offset.
Each 90° elbow (including those provided with the furnace)
of any diameter is equivalent to 1.5m (5 feet ) of vent pipe of
the same diameter. Two 45° elbows are equivalent to one
90° elbow of the same diameter. One 45° elbow is equal to
.76m (2.5 feet) of vent pipe of the same diameter.
In some applications which permit the use of several differ-
ent sizes of vent pipe, a combination vent pipe may be
used. Contact Lennox for assistance in sizing vent pipe in
these applications.
NOTE − The flue collar on all models is sized to accommo-
date 50mm Schedule 40 / Class 12 / Class E pressure
pipe. When vent pipe which is larger than 50mm must be
used in an upflow application, a 50mm elbow must be ap-
plied at the flue collar in order to properly transition to the
larger diameter flue pipe. This elbow must be added to
the elbow count used to determine acceptable vent
lengths. Assign an equivalent meter value to this elbow
according to the larger size pipe being used. Contact
Lennox for more information concerning sizing of vent
systems which include multiple pipe sizes.
305mm Min.
FIGURE 13
Exhaust Pipe Offset
305mm Min.
305mm Min.
305mm Min.
Upflow and Downflow Application
Rooftop Termination
Upflow and Downflow Application
Side Wall Termination
Horizontal Application
Rooftop Termination
Horizontal Application
Side Wall Termination
To Next Page
Loading...
