Operating Instructions

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I. Operation F. Changing Adjustable Parameters (continued)
“Press” button to access the following parameters:
Factory
Setting
Range / Choices Parameter and Description
180°F
(82.2°C)
60°F to 190°F
(16°C to 87.8°C)
Auxiliary Heat Setpoint
Target temperature for the Auxiliary Heat priority. Value also used by the outdoor air reset
function.
170°F
(76.7°C)
80°F to 190°F
(26.7°C to 87.8°C)
Auxiliary 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
setback 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
(5.6°C)
2°F to 25°F
(1.1°C to 14°C)
Auxiliary Heat Diff Above
The boiler stops when the water temperature rises ‘Diff Above’ degrees above the setpoint.
NOTE
Never set the Diff Above such that the Setpoint plus the ‘Diff Above’ is greater than 200°F. the
result may be nuisance manual reset hard lockouts. For example, if the setpoint is 180°F, the
maximum ‘Diff Above’ is 20°F. Further, if the setpoint is 190°F, the maximum ‘Diff Above’ is 10°F.
5°F
(2.8°C)
2°F to 25°F
(1.1°C to 14°C)
Auxiliary 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 Auxiliary Heat temperature controller Proportion Integral Derivative
(PID) values. Higher values cause a larger ring rate change for each degree of temperature
change. If set too high ring rate “overshoots” required value, increases to high re causing the
temperature to exceed the “Diff Above” setpoint and cycle the boiler unnecessarily. Lower values
cause a smaller ring rate change for each degree of temperature change. If set too low, the
ring rate response will be sluggish and temperature will wander away from setpoint.
Disable Disable, Enable
Auxiliary Priority Over Central Heat
This parameter allows the Auxiliary Heat demand to be higher or lower priority than Central Heat
demand. When both demands are active at the same time the Control uses the Setpoint, Diff
Above and Diff Below for the demand that has priority.
Disabled Auxiliary Heat is lower priority than Central Heat demand.
Enable Auxiliary Heat is higher priority than Central Heat demand.
Zone
Control
Zone Control,
DHW Terminal
Auxiliary Heat Demand Source
The Control’s “DHW Temp Switch” input terminal may be used as a Domestic Hot Water (DHW)
demand or Auxiliary Heat demand. When the Domestic Hot Water Demand Source is set to
Zone Control and the Auxiliary Heat Demand Source is set to “DHW Terminal” an Auxiliary Heat
Demand may be wired to the DHW Temp Switch terminals. This feature may be used even if a
Zone Control is not installed.
Zone Control Auxiliary Heat demand may only be wired to the Zone Control
DHW Terminal Auxiliary Heat demand may be wired to the Zone Control or DHW Terminal.
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 red in response to the sensor wired to Header
Sensor Low Voltage Terminal Block Terminals.