Bosch GWH C 800 ES - Vent Length Calculation

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Installation instructions
3.12.2 Vent length calculation
Adjusting the minimum power (P2) based on the
total combined vent length.
After installing the GWH C 800 ES, the minimum power
fan speed must be selected to compensate for variation
in vent pipe length.
Note: See table 4 for maximum vent lengths.
Total vent length calculation
B Determine the total length of all straight sections of
vent pipe and enter in table 7, line 1.
B Count the number of 90° elbows used, multiply by 5,
and enter that value in line 2. (Do not count end
terminal and first elbow after the appliance).
B Count the number of 45° elbows used, multiply by 3,
and enter that value in line 3.
B Repeat steps 1 through 3 for air intake pipe and enter
those values in the intake section of table 7.
B Add line 4 from Exhaust to line 4 of Intake and enter
result in line 5.
This is the total equivalent vent length.
NOTE: If total vent length calculated is 19 feet or
less, no P2 adjustment is needed.
Fittings or Piping Equivalent
feet m
45 degree elbow 3 0.91
90 degree elbow 5 1.52
plastic pipe per foot 1 0.30
concentric vent kit 3 0.91
Table 6 Friction Loss Equivalent in piping and fittings
Exhaust
1
Straight section length __ = ____
2
90° elbows (qty) __ x 5 = ____
3
45° elbows (qty) __ x 3 = ____
4 Total:
____
Intake
1
Straight section length __ x 1 = ____
2
90° elbows (qty) __ x 5 = ____
3
45° elbows (qty) __ x 3 = ____
4
Total: ____
5
Total equivalent vent length = ____
Table 7 Determining vent length combination (see
example in Table 8)