Outdoor Reset Control - Navien NFC-175 Installation & Operation Manual

12.5 Outdoor Reset Control

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. Refer to "11.3.3 Setting the Space Heating Operation" on
page 89 and "11.4.3 Setting the Operation Parameters" on page
95.
The Outdoor Reset Control feature requires installation
Note
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.
Outdoor
High MIN
Absolute
MAX
Absolute
MIN
°F 113 104 95 86 77 68 59 50 41
°C 45 40 35 30 25 20 15 10 5
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.
Outdoor
Low MIN
°F °C
194 90
185 85
176 80
167 75
High Mass Radiant
158 70
Low Mass Radiant
149 65
Cast Iron Baseboard
140 60
131 55
Custom
122 50
Radiator
113 45
104 40
Finned Tube Baseboard
95 35
Fan Coil
86 30
77 25
68 20
59 15
50 10
32 23 14 5 -4 -13
0 -5 -10 -15 -20 -25
Outdoor Temperature Sensor Installation Guidelines
Supply Set Point
Heat Load
Range
Finned Tube 120-180°F
Baseboard (default) (48.5-82°C)
140-180°F
Fan Coil
(60-82°C)
100-170°F
Cast Iron Baseboard
(37.5-76.5°C)
80-140°F
Low Mass Radiant
(26.5-60°C)
80-120°F
High Mass Radiant
(26.5-48.5°C)
120-170°F
Radiators
(48.5-76.5°C)
104-180°F
Custom
(40-82°C)
Outdoor Temperature Range and Default Temperature Settings
Set Point Range
-4°F (-20°C) to
Outdoor Low Outdoor High
Temperature Temperature Set
Point - 9°F (5°C)
Outdoor Low
Outdoor High Temperature Set
Temperature Point + 9°F (5°C) to
104°F (40°C)
Return Set Point
Range
101-147°F
(38-63.5°C)
116-147°F
(46.5-63.5°C)
86-139°F (30-59°C)
70-116°F
(21-46.5°C)
70-101°F (21-38°C)
101-139°F
(38-59°C)
86-149°F
(30-65°C)
Remarks
Default: 14°F
(-10°C)
Default: 70°F (21°C)
Appendixes 113