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Field Wiring Connection
CAUTION: Label all wires prior to disconnection when
servicing controls. Wiring errors can cause improper and
dangerous operation. Verify proper operation after servicing.
A
DANGER: SHOCK HAZARD
Make sure electrical power to the heater is disconnected
to avoid potential serious injury or damage to components.
Wiring the Enable/Disable
Connect the Enable/Disable terminals to the field wiring
terminal. See Figure 22. Alternately, any dry contact
closure (including a remote thermostat) across these
terminals will enable the MVB unit to run. Caution should
be used to ensure neither of the terminals becomes
connected to ground.
Wiring the Outdoor Sensor
1. There is no connection required if an outdoor sensor
is not used in this installation.
2. If using an Outdoor Sensor (option B-32), connect
the sensor wires to the terminals marked OUTDOOR
SENSOR (see wiring diagram). Caution should be
used to ensure neither of these terminals becomes
connected to ground.
3. Use a minimum 18 AWG wire for runs of up to 150
feet.
4. Mount the outdoor sensor on an exterior surface of
the building, preferably on the north side in an area
that will not be affected by direct sunlight and that will
be exposed to varying weather conditions.
FIELD WIRING
TERMINAL BLOCKS
1
2
24VAC
TEMP TO
CWP
INDIRECT
SENSOR
22
NOTE: Use only stranded copper conductors.
4
5
3
6
7
8
9
INDIRECT
SYSTEM
OUTDOOR
DHW
SENSOR
SENSOR
SENSOR
Figure 22. Low Voltage Field Wiring
Wiring the Indirect Sensor
1. An indirect sensor connection is not required if an
indirect water heater is not used in the installation.
2. When the Indirect DHW call for heat is active, the
PIM communicates this to the VERSA. The VERSA
calculates the optimal operation and sends the firing
rate and pump output requests to the PIM so it can
activate the Indirect DHW pump and Boiler pump
as needed. If an optional Indirect DHW sensor
is connected, the PIM will pass this signal to the
VERSA. This allows the VERSA to optimize the
Indirect DHW demand to maintain the Indirect DHW
setpoint. The Indirect DHW thermostat switch closure
is still required when using the Indirect DHW sensor.
If a VERSA is not present the PIM shall activate the
Indirect DHW pump whenever the Indirect DHW
call is active. The Boiler pump will also be activated
based on the Indirect DHW piping configuration
setting. Consult the VERSA IC
for additional configurations.
3. Connect the indirect tank sensor to the terminals
marked INDIRECT DHW SENSOR (see wiring
diagram). Caution should be used to ensure neither
of these terminals becomes connected to ground.
NOTE: Alternately, a thermostat contact closure can be
used in lieu of the sensor for indirect operation. Connect
the thermostat to the terminals marked IND REMOTE
THERMOSTAT.
CAUTION: Sensor and control wiring must NOT be run in
conduit or chases with line voltage.
13
10
11
12
14
15
16
ENABLE/
0 - 10 VDC
DISABLE
CWP
EMS
INDIRECT
INPUT
DHW OVERIDE
JUMPER 11 & 12
WHEN NOT USED
FACTORY WIRING
17
18
19
20
21
22
23
120V
ALARM
EXTERNAL
FAN/DAMPER
EXTERNAL
DRY
INTERLOCK
DRY
SAFETY
CONTACTS
VALVE
CONTACTS
JUMPER WHEN
NOT USED
USE COPPER CONDUCTORS ONLY
®
manual (241493)
24
F10271
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