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FIELD CONNECTED CONTROLLERS
It is strongly recommended that all individually-powered control modules and the heater should be
supplied from the same power source.
WARNING: DO NOT CONNECT ANY SAFETY EXTRA LOW VOLTAGE (SELV) CIRCUIT(S) TO
THIS WATER HEATER.
NOTE: Minimum 1mm, 105°C, stranded wire must be used for all extra low voltage external connections
to the unit (less than 50 volts AC). Solid conductors should not be used because they can cause
excessive tension on contact points. Install conduit as appropriate. All low voltage (120/240V) wires
must be the same size as the ones on the unit or larger (105°C, stranded wire).
Check the Power Source
WARNING: Using a multi-meter, check the following voltages at the circuit breaker panel prior to
connecting any equipment. Make sure proper polarity is followed and earth is proven.
Active to Earth = 216 VAC Minimum, 253 VAC MAX
Active to Neutral = 216 VAC Minimum, 253 VAC MAX
Neutral to Earth = <1 VAC Maximum
Making the Electrical Connections
Refer to
Fig. 35
on page 68.
1. Verify that circuit breaker is properly sized by referring to heater rating plate and pump current
from
Table 19 and 20
NOTE: Current draw noted on rating plate does not include pump current.
2. Turn off all power to the heater. Verify that power has been turned off by testing with a multi-
meter prior to working with any electrical connections or components.
3. Observe proper wire colours while making electrical connections. Many electronic controls are
polarity sensitive. Components damaged by improper electrical installation are not covered by
warranty.
4. Install heater controls, thermostats, or building management systems in accordance with the
applicable manufacturers' instructions.
5. Conduit should not be used as the earth ground.
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.
Wiring the Enable/Disable
Remove the jumper wires and connect the Enable/Disable wires to terminals 11 and 12 marked
'Enable/Disable' shown in
or mechanical air interlock across these terminals will enable the MVB unit to run. Caution should be
used to ensure neither of the terminals becomes connected to earth.
on page 67. A dedicated circuit breaker should be provided.
Fig. 35
on page 68. Any dry contact closure, eg a remote thermostat, flue
75
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