Allied Air Enterprises WARM AIR GAS FURNACE 92G1UH - Manual (Page 17)

506724-01 Page 17 of 57 Issue 1108
Vent Piping Guidelines
This gas furnace can be installed as either a Non-Direct
Vent or a Direct Vent 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
outdoors and flue gases are discharged outdoors.
Intake and exhaust pipe sizing - Size pipe according to Tables
4 and 5. Table 4 lists the minimum vent pipe lengths
permitted. Table 5 lists the maximum pipe lengths permitted.
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 6.
In some applications which permit the use of several different
sizes of vent pipe, a combination vent pipe may be used.
Contact Allied Air Technical Service for assistance in sizing
vent pipe in these applications.
NOTE: It is acceptable to use any pipe size which fits within
the guidelines allowed in Table 5.
NOTE: The exhaust collar on all models is sized to
accommodate 2” Schedule 40 vent pipe. In horizontal
applications, transition to exhaust pipe larger than 2” must
be made in vertical runs of the pipe. A 2” elbow must be
added before the pipe is transitioned to any size larger than
2”. This elbow must be added to the elbow count used to
determine acceptable vent lengths. Contact the Application
Department for more information concerning sizing of vent
systems which include multiple pipe sizes.
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze-ups and
may block the terminations.
IMPORTANT
FIGURE 20
12" max
of straight pipe
Exhaust Pipe
12" Min.
NOTE − Exhaust pipe MUST be glued to furnace exhaust fittings.
NOTE − All horizontal runs of exhaust pipe must slope back to-
ward unit. A minimum of 1/4" (6mm) drop for each 12" (305mm)
of horizontal run is mandatory for drainage.
NOTE − Exhaust piping should be checked carefully to make
sure there are no sags or low spots.
Horizontal Application
Use the following steps to correctly size vent pipe diameter.
1
2
3
4
5
6
045, 070,
090, 110
or 135 btuh
Which termination?
Standard or
Concentric?
See table 3
Intake or
exhaust Which needs
most elbows?
How many?
2", 2 1/2",
3" or 4" Desired pipe size?
Use table 5 to find
max. intake or
exhaust pipe length.
FIGURE 21
What is the altitude?
7
Furnace capacity?
TABLE 4
MINIMUM VENT PIPE LENGTHS
A95UH/A93UH/95G1UH &93G1UH
MODELS
MIN. VENT LENGTH*
045, 070, 090, 110
15 ft. or
5 ft plus 2 elbows or
10 ft plus 1 elbow 135**
*Any approved termination may be added to the minimum length listed.
**This gas furnace must have 3” to 2” reducing ell (supplied or field
replacement Canadian kit) installed directly into unit flue collar.