AHRI K2WT, Installation, Operating And Service Instructions

Page: 118 / 164

118
107110-01 - 6/16
XII. 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.
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 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.
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.
DHW
Demand
Auxiliary Heat,
DHW Demand
DHW Terminal Use
The Control’s “DHW Temp Switch” input terminal may be used as a Domestic Hot Water (DHW)
demand or Auxiliary Heat demand. When the “DHW Terminal Use” is set to Auxiliary Heat a
contact closure sensed at the DHW terminal will cause an Auxiliary Heat to call for heat.
DHW Demand: DHW Heat demand may be wired to DHW Terminal.
Auxiliary Heat: Auxiliary Heat demand may be wired to 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 fired in response to the sensor wired to Header
Sensor Low Voltage Terminal Block Terminals.