Installation instructions
RTG 199 HE – 6 720 811 617 (2016/01)
21
4.3.8
Fan speed adjustment
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 28 and 29. 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.
NOTICE:
IMPORTANT INFORMATION!
▶ Natural gas heaters with installation altitudes below
2,000 ft above sea level disregard this section.
Natural Gas
Liquid
propane
Natural Gas
Liquid
propane
Altitude (above sea
level)
Vent
terminal
Total equivalent vent
length
1)
1) Full equivalent length (inlet + outlet fittings)
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)
Twin
system
3.5 - 11 ft
12
3)
17
3)
52
3)
52
3)
12 - 19 ft
12
3)
17
3)
52
3)
52
3)
2000 - 4500 ft
2)
(610 - 1372 m)
2) When installing in altitude, the unit may not reach the rated Input
Twin
system
3.5 - 11 ft
13
3)
17
3)
52
3)
52
3)
12 - 19 ft
13
3)
3) When adjusting the unit, CO2 levels must be checked with a combustion gas analyzer, see chapter 7.5 for instructions.
17
3)
52
3)
52
3)
Table 27 Fan speed adjustment for 2" piping
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
No
modification
required
No
modification
required
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
Twin
system
6 - 37 ft
38 - 62 ft
2000 - 4500 ft
(610 - 1372 m)
Concentric
6 - 25 ft
11*
14*
52*
52*
26 - 46 ft
11*
14*
53*
53*
Twin
system
6 - 37 ft
10*
13*
52*
52*
38 - 62 ft
11*
14*
53*
53*
4500 - 8000 ft
(1372 - 2439 m)
Concentric
6 - 25 ft
11*
14*
53*
53*
26 - 46 ft
13*
16*
53*
53*
Twin
system
6 - 37 ft
11*
14*
53*
53*
38 - 62 ft
12*
15*
53*
53*
* Above 2000 ft, CO2 levels must be checked with a combustion gas analyzer, see chapter 7.5 for instructions.
Table 28 Fan speed adjustment for 3" piping
1) Full equivalent length (inlet + outlet fittings)
