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Installation instructions
11
Condensate drain requirements
An external condensate drain (not supplied with the
heater) must be installed under the following
conditions:
• All vertical terminating vent installations.
• Horizontal terminating vent installations where the
total linear vent length is greater than 10 feet (3.1 m).
• Vent installations where any section of the exhaust
vent pipe passes through an unconditionedspace.
Twin pipe termination clearances
The minimum clearance between exhaust vent and
combustion air inlet terminations for twin pipe
penetration is 3 feet.
Minimum combustion air and exhaust pipe
length
The minimum exhaust pipe length is 3 feet (1m) of
straight vent pipe. The minimum combustion air pipe
length is one 90° elbow.
Maximum combustion air and exhaust pipe
length
The following table (Table 6) displays the maximum
allowable straight pipe lengths for combustion air and
exhaust piping with consideration to the number of
elbows used.
Step 1: Total the number of 90° elbows and 45°
elbows used on the exhaust piping.
Step 2: Use this value in the table to determine the
maximum straight exhaust pipe length
allowed.
Step 3: Total the number of 90° elbows and 45°
elbows used on the combustion air piping.
Step 4: Use this value in the table to determine the
maximum straight combustion air pipe length
allowed.
* Not allowed. At least one 90º elbow required.
** Not allowed. Minimum of 3 feet (1m) of straight pipe required.
i
Note: 90° elbows used for terminations
should not be counted in the exhaust and
combustion air piping.
Air intake or
Exhaust
system
# of 90° elbows
0 1 2 3 4
# of 45°
elbows
0 N/A* 26 21 16 11
1 N/A* 23 18 13 8
2 23 20 15 10 5
3 20 17 12 7 N/A**
4 17 14 9 4 N/A**
5 14 11 6 N/A** N/A**
6 11 8 3 N/A** N/A**
Maximum allowable straight pipe length (ft)
Table 6 Maximum allowable straight pipe length