Product Overview

47
Boiler Controls
Boiler Controls
McDonnell & Miller
Series 157S
Model 157S-R
G
H
E
D
J
C
F
J
K
A
B
L
A
B
B
B
G
A
A
K
C
F
J
L
J
D
Series 157S
Low Water Cut-Off/Pump Controllers
Low Water Cut-Offs – Mechanical
For Steam Boilers
®
®
• For residential, commercial and industrial low or high
pressure boiler applications
• For boilers of any steaming capacity
• Monel bellows provides corrosion resistance
• Float chamber with integral water column provided
•`Snap action for high temperature service
– 1 Single pole, single throw switch for pump control
– 1 Single pole, double throw switch for low water
cut-off and alarm actuation
• Optional features
– Manual reset
–
Integral conductance probes for additional levels and
greater operating differential-Model 157S-RBP-MD
– 1" or 1
1
⁄4" NPT equalizing tappings
–
1
⁄2" or
3
⁄4" NPT tappings for gauge glass/tri-cock
installations
– BSPT threads
• Maximum pressure 150 psi (10.5 kg/cm
2
)
• For new electronic 150E Series see page 37
Model 157S-MD
Maximum differential operation
– Prevents nuisance burner shutdowns in low pressure
applications
– Maximum operating pressure 50 psi (3.5 kg/cm
2
)
– For additional information see page 48
Dimensions, in. (mm)
Ordering Information
Alarm Circuit Rating (Amperes)
Voltage Amps
120 VAC 1
240 VAC 1/2
Electrical Ratings
Cut-off and Pump
Circuits Rating (Amperes)
Voltage Full Load Locked Rotor Pilot Duty
120 VAC 7.4 44.4
345 VA at
240 VAC
3.7 22.2
120 or 240 VAC
Model
Part Weight
Number Number Description lbs. (kg)
157S 173502 150S low water cut-off w/water column 39.7 (18.0)
157S-MD
173603 157S w/maximum differential
39.7 (18.0)
157S-A 173702 157S w/alternate tappings 39.5 (17.9)
157S-A-M 173802
157S-A w/manual reset 39.5 (17.9)
157S-M 175402
157S w/manual reset 39.7 (18.0)
157S-M-MD 175412 157S-M w/maximum differential 39.7 (18.0)
157S-R 176220 157S w/alternate tappings 42.0 (19.0)
157S-R-M 177306 157S-R w/manual reset 42.0 (19.0)
157S-RBP-MD 176503 157S w/2 integral conductance probes 51.0 (23.1)
157S-RL 176902 157S w/alternate tappings 42.0 (19.0)
157S-RL-M 177006 157S-RL w/manual reset 42.0 (19.0)
Model A
B
C
D
E
FG H JKL
NPT
NPT
NPT
157S
1
1
⁄2 13
3
⁄8 (339)
2
5
⁄16 (59)
4
15
⁄16 (125) 11
3
⁄4 (298)
16 (406)
11
1
⁄2 (292)
3
1
⁄2 (89)
3
⁄4 5
7
⁄8 (149)
157S-A 1
1
⁄4
3
⁄4 13
3
⁄8 (339) 2
5
⁄16 (59) 4
15
⁄16 (125) 11
3
⁄4 (298) 16 (406) 11
1
⁄2 (292) 3
1
⁄2 (89)
3
⁄4 5
7
⁄8 (149)
157S-R 1
1
⁄2 13
3
⁄8 (339) 2
1
⁄4 (57) 5
7
⁄8 (149) 11
3
⁄4 (298) 17 (432) 11
1
⁄2 (292) 3
1
⁄2 (89)
3
⁄4 6
1
⁄4 (159)
157S-RL 1
1
⁄4
1
⁄2 13
9
⁄16 (345) 3
1
⁄2 (89) 5
7
⁄8 (149) 11
3
⁄4 (298) 17 (432) 12
3
⁄4 (324) 3
1
⁄2 (89)
3
⁄4 6
1
⁄4 (159)