WIRING DIAGRAMS
Low Water Cut-Off Only
1. Main Line Switch - For burner circuits within the
switch’s electrical rating.
Pump Control Only
1. Install a starter or relay in pump control circuit,
as shown, to prevent damage to snap switch
and help insure proper switch/control operation.
Failure to do so may shorten the life of the
switch when actual amperage exceeds switch rating.
2. Connect wires from holding coil of pump starter
or relay to terminals 1 and 2 as shown.
NOTE:
To help insure most effective operation,
balance boiler feed pump(s) to deliver required water
feed rate to match boiler steaming requirements.
1. Main Line Switch - For burner circuits within
the switch’s electrical rating.
2. Pilot Switch - To holding coil of a starter when
the burner circuit exceeds the switch’s electrical
rating.
1 2
5 6
SEE PUMP
CONTROL
CIRCUIT
TO BURNER CONTROL CIRCUIT
HOT
1 2
5 6
LOAD
LINE
SEE PUMP
CONTROL
CIRCUIT
1 2
5 6
LOAD
LINE
1 2
5 6
LOAD
LINE
OR
OR
Combination Pump Control, Low Water Cut-Off and Alarm
2. Pilot Switch - To holding coil of a starter when
the burner circuit exceeds the switch’s electrical
rating.
8
LINE
LOAD
1 2
5 6
Summary of Contents for McDonnell & Miller 42S-N Series
Page 1: ...INSTRUCTION MANUAL MM 231G...
