103
Operating the Boiler
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 may only be disabled if the boiler
is not used for any space heating.
11.5.3 Setting the DHW Operation
(Indirect)
To set the boiler’s indirect DHW operation, press
the Menu button (
), and then select “3. 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.
Item
Description
6. 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
Note
This menu is not available
when connecting the AHU
communication type or
cascade mode because
heating is performed only
by controlling the heating
supply water.
* Available only when “4. Outdoor Reset ON/OFF” is set to
“Enabled”.
** 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.
*** 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.
Once the boost interval time expires or the heat load
demand is satisfied, the boiler will then revert back to
its normal space heating settings.
Summary of Contents for NFB-175H
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