Installation instructions
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21
6 720 644 887 (2013/02)
C 1210 ES/ESC
4.3.7
Fan speed adjustment
! IMPORTANT INFORMATION:
Natural gas heaters with installation altitudes below 2,000 ft above sea
level disregard this section.
Installation adjustment:
After installing the tankless 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. This is the straight pipe
length of both exhaust and combustion air plus the number of elbows
used. To determine the length equivalency of each elbow refer to tables
8 and 9.
Use the equivalent vent length value to determine the appropriate fan
speed values found in table 21 and 22. Refer to page 22 on how to adjust
the fan speeds if an adjustment is necessary. After changing fan speed
values, proceed to chapter 7.5 to confirm CO
2
values are within
specified ranges.
Natural Gas
Liquid
propane
Natural Gas
Liquid
propane
Altitude (above sea
level)
Vent
terminal
Total equivalent vent
length
1)
Minimum
power fan
speed (P2)
Minimum
power fan
speed (P2)
Maximum
power fan
speed (P1)
Maximum
power fan
speed (P1)
0 - 2000 ft
(0 - 610 m)
Concentric
6 - 25 ft
12
12
No
modification
required
No
modification
required
For operation at
elevations above
2,000 ft (610 m)
the equipment
ratings shall be
reduced at the rate
of 4% for each
1,000 ft (305 m)
above sea level
26 - 46 ft
12
13
Twin
system
6 - 37 ft
12
12
38 - 62 ft
12
14
2000 - 4500 ft
(610 - 1372 m)
Concentric
6 - 25 ft
12*
14*
26 - 46 ft
13*
14*
Twin
system
6 - 37 ft
12*
13*
38 - 62 ft
13*
14*
4500 - 8000 ft
(1372 - 2439 m)
Concentric
6 - 25 ft
13*
14*
26 - 46 ft
13*
15*
Twin
system
6 - 37 ft
13*
14*
38 - 62 ft
13*
15*
* Above 2000 ft, CO2 levels must be checked with a combustion gas analyzer, see chapter 7.5 for instructions.
Table 21 Fan speed adjustment for 3" piping
1) Full equivalent length (inlet + outlet fittings)
Natural Gas
Liquid
propane
Natural Gas
Liquid
propane
Altitude (above
sea level)
Vent
terminal
Total equivalent vent
length
1)
Minimum
power fan
speed (P2)
Minimum
power fan
speed (P2)
Maximum
power fan
speed (P1)
Maximum
power fan
speed (P1)
0 - 2000 ft
(0 - 610 m)
Concentric
3.5 - 39 ft
12
12
No
modification
required
No
modification
required
For operation at
elevations above
2,000 ft (610 m) the
equipment ratings
shall be reduced at
the rate of 4% for
each 1,000 ft (305
m) above sea level
40 - 86 ft
12
13
Twin
system
3.5 - 59 ft
12
12
60 - 126 ft
12
14
2000 - 4500 ft
(610 - 1372 m)
Concentric
3.5 - 39 ft
12*
14*
40 - 86 ft
13*
14*
Twin
system
3.5 - 59 ft
12*
13*
60 - 126 ft
13*
14*
4500 - 8000 ft
(1372 - 2439 m)
Concentric
3.5 - 39 ft
13*
14*
40 - 86 ft
13*
14*
Twin
system
3.5 - 59 ft
13*
14*
60 - 126 ft
13*
15*
* Above 2000 ft, CO2 levels must be checked with a combustion gas analyzer, see chapter 7.5 for instructions.
Table 22 Fan speed adjustment for 4" piping
1) Full equivalent length (inlet + outlet fittings)
