11
Pump Exercising
If the system pump has not operated at least once
every 70 hours, the control turns on the output for 10
seconds. This minimizes the possibility of the pump
seizing during a long period of inactivity.
Setpoint Operation
A setpoint is a fixed water temperature target that the
heater is to maintain at the system sensor. The heater
maintains the heater target by operating the stages
using the proportional or the PID logic together with
the heater differential. The setpoint temperature is set
using the BOIL TARGET item in the adjust menu.
Mode 2 and Enable (Dem 1)
A call for heat (CFH) is required whenever heat is
required for the primary heating load. This CFH is
generated when 24VAC is applied across the
enable/disable connection P1 (terminals 1 and 2).
Once the voltage is applied, the control turns on the
Dem 1 segment in the display and the controller oper-
ates the heater stages to maintain the BOIL TARGET
1 at the system sensor.
Mode 2, 5 and 7, and Domestic Hot
Water Override (Dem 2)
A CFH is required whenever heat is required for the
secondary heating load such as an indirect domestic
hot water tank. A CFH is generated when 24VAC is
applied across the DHW contacts P1 (terminals 1 and
3). Once the voltage is applied, the control turns on the
Dem 2 segment in the display and the controller oper-
ates the heater stages to maintain the BOIL TARGET
2 at the system sensor.
Dedicated Domestic Hot Water
(DHW) Operation
When mode 3 is selected, the Controller provides ded-
icated DHW operation.
Internal DHW Demand
A sensor is required to be installed in the tank and con-
nected to the
Com
and the
Sys/D
terminals (6 and 4).
A CFH for DHW is generated when the temperature at
the DHW sensor drops 1/2 of the tank differential set-
ting below the desired DHW tank temperature. The
TANK TARGET setting is used to set the desired DHW
tank temperature. Once a CFH is generated, the
Dem
segment turns on in the LCD.
The Controller then operates the heater stages to
maintain the programmed heater target temperature at
the heater system sensor located in the tank. The
heater target temperature is set using the BOIL TAR-
GET item in the adjust menu.
Tank Differential (TANK DIFF)
A differential setting that operates 1/2 above and
below the TANK TARGET is selectable using the
TANK DIFF item in the adjust menu.
Outdoor Reset Operation
When Mode 5 is selected, the Controller uses outdoor
reset to control the water temperature. Outdoor reset
adjusts the target temperature based on the outdoor
air temperature and the reset ratio; as the outdoor air
temperature rises, the need for heat drops and the set-
point is reduced The reset ratio is determined from the
Heater Start, Heater Design, Outdoor Start and
Outdoor Design settings.
Enable/Disable
A CFH is generated when a voltage of 24 VAC is
applied across the Enable/Disable terminals (1 and 2).
Once voltage is applied, the Controller turns on the
Dem 1
segment in the display. If the Controller is not
in Warm Weather Shut Down (WWSD), it then oper-
ates the heater stages to maintain the heater target
temperature.
NOTE:
If the controller is in WWSD, the WWSD
segment is shown in the display and the heater tar-
get in the view menu of the display remains “ - - - “
(no target).
WARNING:
Verify closure across Enable/Disable
contacts P1, terminals 1 and 2. DO NOT use DHW
override on terminal 3.
