U.S. Boiler Company Alpine ALP500C, Installation, Operating And Service Instructions

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100
X. Operation
F. Changing Adjustable Parameters (continued)
“Press”
Central
Heat
button to access the following parameters:
Factory
Setting
range / Choices Parameter and Description
180°F
(82.2°C)
50°F to 190°F
(10°C to 87.8°C)
Central Heat Setpoint
Target temperature for the central heat priority. Value also used by the outdoor air reset function.
170°F
(76.7°C)
50°F to 190°F
(10°C to 87.8°C)
Central Heat Thermostat “Sleep” or “away” Setback Setpoint
Thermostat setback setpoint is used when the EnviraCOM thermostat is in “leave” or “sleep”
modes and sensed at E-COM terminals D, R, and C. When setback is “on” the thermostat set -
back setpoint shifts the reset curve to save energy while home is in a reduced room temperature
mode. The reset curve is shifted by the difference between the High Boiler Water Temperature
and the Thermostat Setback Setpoint. Honeywell VisionPro IAQ part number TH9421C1004 is a
“setback” EnviraCOM enabled thermostat. When connected, it allows boiler water setback cost
savings.
10°F
(-12.2°C)
2°F to 25°F
(-16.7°C to 3.9°C)
Central Heat Diff above
The boiler stops when the water temperature rises ‘Diff Above’ degrees above the setpoint.
5°F
(-15.0°C)
2°F to 25°F
(-16.7°C to 3.9°C)
Central Heat Diff Below
The boiler starts when the water temperature drops ‘Diff Below’ degrees below the setpoint.
3 1 to 5
response Speed
This parameter adjusts the Central Heat temperature controller Proportion Integral Derivative
(PID) values. Higher values cause a larger firing rate change for each degree of temperature
change. If set too high firing rate “overshoots” required value, increases to high fire causing the
temperature to exceed the “Diff Above” setpoint and cycle the boiler unnecessarily. Lower values
cause a smaller firing rate change for each degree of temperature change. If set too low, the
firing rate response will be sluggish and temperature will wander away from setpoint.
120
seconds 0 to 1800 seconds
Low Fire Hold Time
“Low Fire Hold Time” is the number of seconds the control will wait at low fire modulation rate
before being released to modulate. After ignition and flame stabilization periods the firing rate is
held at low fire for “Low Fire Hold Time”. This delay allows heat to travel out to the system and
provide system feedback prior to the control modulating firing rate.
Supply
Sensor
Supply Sensor,
Header Sensor
Modulation Sensor
Heat Demand may respond to the boiler’s Supply Temperature or Header Temperature sensors.
When Header Sensor is selected the boiler is fired in response to the sensor wired to Header
Sensor terminals.
nOTE: When Header Sensor is selected, also set Boiler Pump parameter to Header Sensor
Demand/Combustion Air Damper.