Navien NFC-175, Installation & Operation Manual

Page: 90 / 124

90 Operating the Boiler
Item Description
2-3. Outdoor Low
Temp Set**
Set the maximum temperature for the
Outdoor Reset Control.
●
Setting range: -4°F (-20°C) – [MAX Set-
point – 9°F (5°C)]
●
Default: 14°F (-10°C)
2-4. WWSD Temp
Set the Warm Weather Shut-down
temperature.
●
Setting range: OFF, 50°F (10°C) –
104°F (40°C)
●
Default: OFF
2-5. WWSD On Diff
Set the differential temperature to
deactivate the Warm Weather Shut-
down.
●
Setting range: 0°F (0°C) – 36°F (20°C)
●
Default: 5°F (3°C)
2-6. Boost Interval
Time***
Set the boost interval time.
●
Setting range: 0 – 120 min
●
Default: 0 min
3. Navien zone cont.
Enable or disable heating zones utilizing
the Navien Zone Controller.
●
Setting range: Enabled/Disabled
●
Default: Disabled
4. SH Control
Method
Select a heating control type.
1: Supply Temperature
2: Return Temperature
3: Sys Supply Temperature
4: Sys Return Temperature
●
Default: Supply Temperature
* A preset or user defined temperature range is set automatically based on
the curve selected. Refer to the settings table for details.
Heat Load
Supply Set
Point Range
Return Set
Point Range
Remarks
1. Finned Tube
Baseboard
120–180°F
(48.5–82°C) 101–147°F
(38–63.5°C)
Default
2. Fan Coil
140–180°F
(60–82°C) 116–147°F
(46.5–63.5°C)
3. Cast Iron
Baseboard
100–170°F
(37.5–76.5°C) 86–139°F
(30–59°C)
4. Low Mass
Radiant
80–140°F
(26.5–60°C) 70–116°F
(21–46.5°C)
5. High Mass
Radiant
80–120°F
(26.5–48.5°C) 70–101°F
(21–38°C)
6. Radiators
120–170°F
(48.5–76.5°C) 101–139°F
(38–59°C)
7. Custom
104–180°F
(40–82°C) 86–149°F
(30–65°C) User-
defined
Heat loads 1-6 show the preset temperature ranges based on the load
type selected, while heat load 7 provides a custom temperature range.
When the custom temperature range is in use, the boiler operates based
on the user–defined “Absolute Min” and Absolute Max” temperature
settings.
** Available only when “2. Outdoor Reset ON/OFF” is set to “Enabled”.
*** The boost interval time may be set to prevent interruption in space
heating while using the Outdoor Reset Control mode, due to changes
in heat load conditions. With the boost interval time enabled, the boiler
increases the space heating supply temperature by 9°F (5°C) and the
return temperature by 5°F (3°C) after a set time elapses.
CAUTION
An outdoor sensor error may occur if the Outdoor Reset
Control mode is enabled without the outdoor sensor installed
Note
In the Outdoor Reset Control mode, the boiler’s water
temperature is regulated according to the outdoor
temperature to maximize boiler efficiency and reduce
energy usage. This mode must remain enabled and
the outdoor sensor must be installed to comply with
federal efficiency regulations. The Outdoor Reset mode
cannot be used when using the DHW mode.
11.3.4 Setting the DHW Operation
To set the boiler’s DHW operation, press the Menu button
( ), and then select “4. DHW Operation”.
Rotate the Command dial ( ) to switch between the list items or
to increase/decrease setting values. Press the Command dial ( )
to select an item or to confirm after making changes.