Electrical Connections - Mr. Heater MHU 50 Mode D'emploi

LINE VOLTAGE FIELD WIRING
L1
N
EQUIPMENT
GROUND
BLACK WIRE WITH WHITE TAPE OR
WHITE WIRE WITHOUT TAPE
FIGURE 7
GAS SUPPLY CONNECTION
GROUNDED
JOINT UNION
DRIP LEG
FIGURE 8
GAS SUPPLY TO UNIT HEATER
MANUAL MAIN SHUT-OFF
VALVE WILL NOT HOLD
NORMAL TEST PRESSURE
CAP
UNIT HEATER
FIGURE 9
UNIT
BLACK
BLACK
WHITE
WHITE
MANUAL
MAIN SHUT-OFF VALVE
(FURNISHED BY INSTALLER)
GAS FLOW
ISOLATE
GAS VALVE
Compact Unit / Utility Heater
5. Test for spillage at the draft hood relief opening after five
minutes of main burner operation. Use the flame of a match
or candle, or smoke from a cigarette, cigar, or pipe.
6. After it has been determined that each appliance remaining
connected to the common venting system properly vents
when tested as outlined above, return doors, windows,
exhaust fans, fireplace dampers and any other gas-burning
appliance to their previous condition of use.
7. If improper venting is observed during any of the above tests,
the common venting system must be corrected. The common
venting system should be resized to approach the minimum
size as determined by using the appropriate tables

ELECTRICAL CONNECTIONS

NOTE: The MHU series unit/utility heaters use a direct spark
ignition system. There is no pilot necessary as the spark lights
the main burner as the gas valve is turned on. The direct spark
ignition control board emits radio noise during burner ignition.
The level of energy may be enough to disturb a logic circuit in a
microprocessor controlled thermostat. It is recommended that
an isolation relay be used when connecting the unit heater to a
microprocessor controlled thermostat. Select circuit protection
and wire size according to the unit rating plate. Install a separate
disconnect switch (protected by either fuse or circuit breaker) near
the unit so that power can be turned off for servicing. Remove
electrical junction box cover and connect wiring through knockout
on the junction box located on the side of the heater. Refer to
heater wiring diagram for connection information. Use 18 gauge
wire or larger for line power connections. Make sure to connect
line power to wires located in the external electrical junction box
behind junction box cover. DO NOT CONNECT LINE POWER TO
THERMOSTAT TERMINAL STRIP ON OUTSIDE OF HEATER.
Electrically ground the unit in accordance with local codes or
in the absence of local codes, in accordance with the current
National Electrical Code (ANSI/NFPA No. 70) in the USA, and in
Canada with the current Canadian Electrical Code, Part 1 CSA
C22.1
NOTE: Un-insulated ground wire must be warped in electrical
tape to avoid damage to the electrical system.
Make line voltage connections as shown in figure 7. Connect
field wiring as shown on wiring diagram on unit. Also, refer to
typical diagram in this manual.
To use the blower for air circulation only, your thermostat
must have a „fan only‰ or fan selection setting. In case your
thermostat has this option. an additional wire should be run to
the „G‰ terminal on the thermostat connection block. See wiring
schematic on page 13.
9
Operating Instructions and OwnerÊs Manual