Installation / Operation Instruction Manual

39
Installation instructions
RTG-K-199/160N/X1 – 6 720 817 984 (2022/06)
4.11 Domestic hot water recirculation with
external pump
The following drawing is provided to outline one possible
recirculation design. This schematic is for illustration only and
must not be used for actual installation without appropriate
engineering and technical advice from a properly licensed
professional in the locality where the installation is made.
This appliance has been designed to permit recirculation by
controlling an external pump. For this function a cable has been
provided to electrically connect the external pump to the
appliance. All the features of recirculation ( section 6.5.4 A1
Recirculation) can be used. Please be aware that the cable
does not provide 120 VAC to operate the recirculation pump, it
is a dry-contact switching external voltage of up to a maximum
of 5 amps.
Fig. 30 Recirculation application
[1] Cold water supply
[2] Check valve
[3] Circulator pump
[4] Expansion tank
[5] Shutoff valves, field supplied
[6] PRV
[7] RTG-K-160/199N/X1
4.12 Adjusting the recirculation settings
The pump and burner turn ON and OFF based on a delta
between the set point temperature on the water heater and the
inlet water temperature sensor value. This delta is called the
comfort level.
The higher the comfort level, the smaller the delta between the
set point temperature on the water heater and the inlet water
temperature sensor value, resulting in a hotter recirculation
system.
The smaller the comfort level, the larger the delta between the
set point temperature on the water heater and the inlet water
temperature sensor value, resulting in a cooler recirculation
system.
Below is a graph illustrating how the comfort level value
changes the recirculation system’s temperature.
Fig. 31 Pump activation and deactivation thresholds
Table 18 RS Menu
The comfort level can be adjusted to achieve the desired
balance between readiness of hot water at the point of use and
energy consumption.
A higher comfort level will result in longer pump run times,
which will consume more electricity and gas.
6720816948-24.1V
4
3
7
6
2
5
1
Comfort level Delta T ( °F)
118
2 16
314
4 12
510
6 8
76
8 4
92
Set point
Adjustable within hidden RS menu (2-18F)
Pump OFF
10F
Pump ON
Water temp in loop (inlet water NTC)
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