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Installation instructions
17
3.3.6 Fan speed adjustment
IMPORTANT! Installation adjustment:
After installing the water heater, the fan speed values for
minimum power (P2) and maximum power (P1) may
need adjustment due to variations in altitude and vent
pipe length.
Failure to make necessary adjustments to fan speed
values may result in improper operation of the
appliance.
First calculate the total equivalent vent length. Use this
value to determine the appropriate fan speed values,
found in Table 12 and make any necessary
adjustments. After changing fan speed values proceed
to Section 6.4 to confirm CO
2
values are within
specified ranges.
Total equivalent vent length calculation
B Determine the total length of all straight sections of
vent pipe and enter in table 10, line 1.
B Count the number of 90° elbows used and enter that
value in line 2. (Do not count terminals and first elbow
used on intake and exhaust).
B Count the number of 45° elbows used 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 10.
B Add line 4 from Exhaust to line 4 of Intake and enter
result in line 5.
This is the total equivalent vent length.
Example
Exhaust
• 7 - 3' straight sections
• 1 - 1' straight section = Total straight pipe length 22’
• 2 - 90° elbow.
Intake
• 5 - 3' straight sections =
Total straight pipe length 15’
• 1 - 90° elbows.
Example
Note: Do not count terminals and first elbow used on
intake and exhaust.
Exhaust
1
Straight section length
(feet)
__ x 1 =
____
2
90° elbows (qty) __ x 2.5 =
____
3
45° elbows (qty) __ x 1.25 =
____
4 Total:
____
Intake
1
Straight section length __ x 1 =
____
2
90° elbows (qty) __ x 2.5 =
____
3
45° elbows (qty) __ x 1.25 =
____
4
Total:
____
5
Total equivalent vent length =
____
Table 10 Determining vent length combination (see
example in Table 11)
Exhaust
Straight section length
(feet)
22 x 1 = 22
90° elbows (qty) 1 x 2.5 = 2.5
45° elbows (qty) 0 x 1.25 = 0
Total: 24.5
Intake
Straight section length
(feet)
15 x 1 = 15
90° elbows (qty) 1 x 2.5 = 0
45° elbows (qty) 0 x 1.25 = 0
Total: 15
Total equivalent vent length = 39.5
Table 11 Determining vent length combination exam-
ple
i
Total equivalent length must not to
exceed 57ft.
i
NOTE: If using concentric terminal include
exhaust pipe length that is part of the con-
centric terminal.