Navien NCB-20LHWE, Installation & Operation Manual

Page: 17 / 80

2.6.2 Operating According to Outdoor
Temperature Conditions
The Outdoor Reset Control feature may be used to enhance
energy efficiency while maintaining optimal heating
performance. With the Outdoor Reset Control, the space heating
temperature setting automatically changes according to the
outdoor temperature and the current space heating system
application (system load).
You can configure the Outdoor Reset Control settings on the
front panel by entering the Special Parameter Setting mode.
Refer to “11.5 Setting the Parameters” on page 48.
Note
The Outdoor Reset Control feature requires
installation of an outdoor temperature sensor, and it
only works when the boiler is running in the normal
operation mode. It does not work when the boiler is
running in either the Minimum (MIN) or Maximum
(MAX) mode, or when the boiler’s front panel displays
a fault.
45 40 35 30 25 20 15 10 5 0 -5 -10 -15 -20 -25
185
194
176
167
158
149
140
131
122
113
104
95
86
77
68
59
50
113 104 95 86 77 68 59 50 41 32 23 14 5 -4 -13 °F
°C
85
90
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
°F °C
Absolute
MAX
Absolute
MIN
Outdoor
High MIN
Outdoor
Low MIN
High Mass Radiant
Low Mass Radiant
Cast Iron Baseboard
Custom
Radiator
Finned Tube Baseboard
Fan Coil
Space Heating Temperature Setting for the
Outdoor Reset Control Feature
The following tables list the default space heating temperature
range by system heat load and the applicable outdoor
temperature ranges.
Note
To connect the outdoor temperature sensor to the
boiler, carefully follow the connection instructions
provided in the “13.5 Outdoor Temperature Sensor
(Optional)” on page 72.
2.6 Operating Modes
2.6.1 Operating in Space Heating Mode
To operate the Space heating mode, press the Space heating
button on the front panel and select a heating temperature
setpoint higher than current heating temperature.
1. When the boiler detects a request for heating production
(from the installation’s room thermostat, for example), the
3-way valve goes to heating position and the circulating
pump starts up.
2. If the boiler water temperature is lower than the desired
temperature setpoint, the boiler ignites and heats up the
heating installation until the selected boiler temperature
is reached. The boiler’s electronic control modulates
the burner output to adapt to the installation’s heat
requirements at all times and so that the installation’s water
temperature remains constant. This prevents the installation
from overheating and reduces heat loss as much as possible.
3. When there is no further heating demand (e.g. when
the desired ambient temperature selected on the room
thermostat is reached), the burner is extinguished (if it was
ignited) and the circulation pump continues to run during
the post-circulation time (minimum 3 minutes), to protect
the boiler from overheating due to thermal inertia in the
installation.
Air In Air In
Exhaust
Gas
Blow Fan
Ignitor
Gas
Valve
Gas
Inlet
Flow
Out
CH
Return
Circulation
Pump
Heat
Exchanger
2.7 Installation Procedure
The flow diagram below provides a step-by-step description of the recommended procedure for clear, easy installation of the NCB LHWE
boiler in its final location. A detailed description is given of the procedure in the sequenced sections below:
Wall-mounting
»
Gas connection
»
Electrical connections
»
DIP switch settings
»
Final check
»
Water and condensate
pipe connection
»
Flue gases exhaustion
system installation
(if necessary)
»
Gas changeover
(if necessary)
»
Boiler operation
»
p. 18
p. 21
p. 25
p. 35
p. 34
5 4 . p 4 4 . p
p. 28
p. 61
17 About the Boiler