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10
Operation
(continued)
10. Outdoor Reset Parameters
Select
to access the following parameters.
Outdoor Reset Enable
If an outdoor sensor is installed and Outdoor Reset is Enabled, the boiler will automatically adjust
the heating set point temperature based on the outdoor reset curve in (see Figure 10-21). The
maximum set point is defined by the Central Heat Setpoint (default 180°F) when the outdoor
temperature is Min Outdoor Temp (default 32°F) or below. The minimum set point temperature
shown is 130°F when the outdoor temperature is 50°F or above. As the outdoor temperature falls
the supply water target temperature increases.
Disable
Do Not Calculate setpoint based on outdoor temperature
Enable
Calculate the temperature setpoint based on outdoor temperature using a reset
curve defined by Low Outdoor Temp, High Outdoor Temp, Low Boiler Water Temp,
Min Boiler Temp and Central Heat Setpoint and Boost Time parameters.
Minimum Outdoor Temperature
Also called "Outdoor Design Temperature". This parameter is the outdoor temperature used in the
heat loss calculation. It is typically set to the coldest outdoor temperature.
Maximum Outdoor Temperature
Outdoor temperature at which the Low Water Temperature is supplied. This parameter is typically
set to the desired building temperature.
Low Water Temperature
Operating setpoint when the Maximum Outdoor Temperature is measured. If the occupied space
feels cool during warm outdoor conditions, the Low Water Temperature parameter should be
increased.
Minimum Boiler Water Temperature
Sets a low limit for the Reset setpoint. Set this parameter to the lowest supply water temperature
that will provide enough heat for the type radiation used to function properly. Always consider the
type of radiation when adjusting this parameter.
Central Heat Outdoor Reset Max Off Point
Maximum value the setpoint can reach due to boost function. Should be set to match Central
Heat Setpoint plus Differential Above.
Lead/Lag CH Outdoor Reset Max Off Point
Maximum value the setpoint can reach due to boost function. Should be set to match Central
Heat Setpoint plus Differential Above.
Boost Time
When the Central Heat Setpoint is decreased by Outdoor Reset settings, the Boost Time
parameter is used to increase the operating setpoint when the space heat demand is not satisfied
after the Boost Time setting is exceeded. When heat demand has been "on" continuously for
longer than the Boost Time parameter the operating setpoint is increased by 10°F (5.6°C). The
highest operating setpoint from Boost Time is current Central Heat Setpoint minus the Central
Heat "Diff Above" setting. A setting of 0 seconds disables this feature.
106308-05 - 3/23
Parameter and Description
APEX
Installation, Operating, & Service Instructions
Factory
Range /
Setting
Choices
Enable
Enabled
Disable
0°F
-50 to 32°F
(-18°C)
(-45.6 to 0°C)
70°F
35 to 100°F
°C)
°C)
(21.1
(1.7 to 37.8
110°F
70 to 180°F
°C)
°C)
(43.3
(21.1 to 82.2
130°F
50 to 185°F
°C)
°C)
(54.4
(10 to 85
190°F
50 to 190°F
°C)
°C)
(87.8
(10 to 87.8
190°F
50 to 190°F
°C)
°C)
(87.8
(10 to 87.8
0 min.
0 to 30 min.
97
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