Page 38
WARNING
When servicing the controls, label all wires prior to
disconnection. Wiring errors can cause improper
and dangerous operation. Verify proper operation
after servicing.
DHW –
if an aquastat, end switch (isolated contact
only), or flow switch is used as a DHW heat demand,
connect to terminals 41 and 42. If preferred, a DHW
tank sensor can be used in lieu of an aquastat to
generate a heat demand (see Sensors section above).
NOTE: CH1/DHW1, CH2/DHW2, and DHW heat
demand contacts must be dry contacts. The controllers
heat demand voltage is 24VDC.
7.E.7 Spare Inputs
There is no functionality associated with these inputs.
7.E.8 Inputs, BMS
BMS
– if an analog input (0-10VDC or 4-20mA) from a
Building Management System is used as a remote set
point or remote firing rate command, wire to terminals
47 and 48 (See Figure 14 on page 36). Polarity
is shown on the terminal label. Selecting voltage or
current input is accomplished through jumper placement
on the control board. Analog BMS functionality is
configured using the touch screen.
7.E.9 Outputs, Pump
Pump
– when using Vari-Prime pump control, wire the
pump speed wires to terminals 49 and 50. Polarity
is shown on the terminal label. Selecting voltage
or current output is accomplished through jumper
placement on the control board. Vari-Prime functionality
is configured using the touch screen.
7.E.10 Dry Contacts (Run & Alarm)
Run
- when used, is connected to terminals 51
(common), 52 (normally closed), and 53 (normally
open) (See Figure 14 on page 36). The controller
closes the normally open set of contacts whenever
the unit is running. Contact ratings are 250VAC, 0.6A
maximum.
Alarm
- when used, is connected to terminals 54
(common), 55 (normally closed), and 56 (normally
open). The controller closes the normally open set
of contacts whenever the unit is locked out. Contact
ratings are 250VAC, 0.6A maximum.
7.E.5
Sensors
System Supply
- if used, is connected to terminals 29
and 30. When connected, the controller automatically
detects the presence of this sensor and the temperature
is shown on the home screen above the red system
supply arrow. When installed, the unit controls the firing
rate to maintain the system supply temperature to the
heat demand set point (or CSP) and hysteresis.
System Return
- if used, is connected to terminals 31
and 32. When connected, the controller automatically
detects the presence of this sensor and the temperature
is shown on the home screen above the blue system
output arrow.
Domestic Hot Water
(DHW) - if a tank sensor is used,
connect to terminals 33 and 34. When connected, the
unit will automatically detect the presence of this sensor
and perform the DHW thermostat function based on the
settings selected at DHW or DHW3 parameter screens.
The temperature is displayed on the home screen below
the faucet icon. The controller initiates a call for heat,
maintaining the set point within the on and off hysteresis
selected at DHW or DHW3 demand screen, without any
need for jumpers.
Note:
The Heat Demands at 33 to 34 are used for
sensors only, aquastats would be applied to the “Heat
Demand” terminals 41 and 42 (see Heat Demands
section below).
Outdoor
- if used, is connected to terminals 35 and 36.
When connected, the controller automatically detects the
presence of this sensor and the temperature is shown on
the home screen as the Outdoor Ambient Temperature
(OAT). If installed, options such as outdoor reset and
warm weather shutdown can be enabled through
the display. Always install the Outdoor Sensor at an
outdoor location that is not affected by false temperature
readings such as sunlight or hot equipment.
7.E.6
Heat Demands
(Boiler / Water Heater)
CH1/DHW1 -
if a thermostat/aquastat or end switch
(isolated contact only) is used as a heat demand,
connect to terminals 37 and 38 . CH1/DHW1
functionality is configured on the touch screen on the
CH1/DHW1 screens.
CH2/DHW2 –
if an additional thermostat/aquastat or
end switch (isolated contact only) is required as a heat
demand, connect to terminals 39 and 40. CH2/DHW2
functionality is configured on the touch screen on
CH2/DHW2 screens.
LAARS Heating Systems
