After proper wiring and piping of boiler system is complete, testing of
controls can start.
Before testing controls, it is recommended that
all contactor fusing be removed.
This is to prevent possible element
failure under test conditions.
A. OPERATING AND TESTING THE McDONNELL &
MILLER LOW WATER CUTOFF CONTROL.
1.
Be sure all valves from incoming water supply are fully open.
Turn boiler switch to “ON” position,
pump or solenoid
valve will energize, allowing boiler to fill with water. Proper
water level is automatically reached with level control sup-
plied. Pump or solenoid feed will shut off at proper water level.
Contactor(s) will energize, supplying power voltage to ele-
ments.
2. Checking operation of pump switch.
(Figure 1) With water
level visible in sight glass, partially open drain valve at bottom
of boiler. If automatic blowdown supplied, push manual blow-
down switch until valve open light is on, hold for few seconds.
Water level will fall, allowing float to trip pump switch to
“ON” position. Close drain valve or release manual blowdown
switch.
Pump motor or solenoid valve will energize and water level
will resume to normal level in sight glass.
3. Checking low water cutout switch operation,
open drain
valve completely. If automatic blowdown supplied, push in
and hold manual blowdown switch until water level falls
enough to trip cutout switch. Close drain valve or release man-
ual blowdown switch. If low water cutout is automatic reset,
pump or solenoid will return water level to normal. If low
water cutout is manual reset, then manual reset button on
McDonnell & Miller low water cutoff control must be pushed
to complete circuit.
Turn off boiler. Reinstall contactor
fuses.
WARNING:
Be sure all electrical connections are tight
before energizing boiler. Reset all manual reset con-
trols by pushing reset buttons on: (1) high limit control
located on top of boiler and (2) McDonnell & Miller
located on the side of boiler.
Diagram 14
TYPICAL WIRING DIAGRAMS
3
GND
C1
CR
C2
C3
2PS
1PS
On
Off
FU16
IFS
O
O
Y
BR
B
B
1PB
1
2
W
R
Boiler
On
9.9
Heater Contactor
1LT
2 HTR
1 HTR
1L1
1L3
1L2
2L1
2L3
2L2
C1
C2
FU1
FU9
FU8
FU7
FU6
FU5
FU4
FU3
FU2
C3
3 HTR
3L1
3L3
3L2
L1
L3
L2
1
GND
2
GND
Heater Contactor
FU12
FU11
FU10
C4
4 HTR
4L1
4L3
4L2
Heater Contactor
Heater Contactor
346V 3Ø 50 HZ
220 VAC Single Phase Control Circuit
1
C4
1CR-1
BW
1CR-2
Customer Pump
Connection
FU
1 2 3
FU
4 5 6
FU
7 8 9
C1
C4
C2
3
HTR
2
HTR
1
HTR
4
HTR
1
2
2TB 1TB
3
GND
2
GND
1
GND
FU16
1PB
Cabinet Exterior Left Side
Cabinet Exterior Right Side
Panel Layout
Feed Water
Electrical
Connection
FU
10
11 12
C3
1CR
FU13
FU14
FU15
5L1
5L3
5L2
1
Mtr
Customer
Connect
Feed Water
Motor
10L
30L
20L
IT1
IT3
IT2
CR
Wire Color Code
B
= Black
BR = Brown
R
= Red
O
= Orange
Y
= Yellow
G
= Green
BL = Blue
W = White
11
A
C
D
B
Line
Pump
Low-Water
Cut-Off
Terminals
Alarm
Circuit
Terminals
Pump
Circuit
Terminals
Pump
Switch
Cut-off
and
Alarm
Switch
Adjusting
Screws
Figure 1
— Automatic Reset Low-Water Cutoff Junction Box
PRE-OPERATION CHECK
