20 | Installation instructions
4.6.3 Vent specifications
Establish vent clearances that comply with the vent
manufacturer's specifications and all applicable national/local
Minimum combustion air and exhaust pipe length
The minimum exhaust pipe length is 1 foot (0.3m) of straight
vent pipe. The minimum combustion air pipe length is one 1 ft
or one 90° elbow or an air intake grill cap to prevent debris from
falling into the appliance.
Maximum combustion air and exhaust pipe length
The table 8 displays the maximum allowable straight pipe
lengths for combustion air and exhaust piping. Reduce the
maximum allowable pipe length by the equivalent lengths for
each elbow used and termination used.
PROPER GAS PRESSURE!
The following section assumes the water
heater will receive greater than or equal to 5"
WC. In cases of gas pressure below 5" WC
and long vent runs, the water heater's output
power may be reduced.
The values of maximum flue length in
table 8 are before any deductions for
elbows or terminations.
2" Twin pipe
3" Twin pipe
Maximum Allowable Exhaust and Combustion Air
6 720 816 815 (2016/10)
Greentherm 9800 SE 160/199 | SEC 199