Xylem MM 219J User Manual
Replacement Head Mechanism
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Snap Switch
Models:
150S-HD
150S-M-HD
150S-MD-HD
150S-M-MD-HD
158S-HD
158S-M-HD
158S-MD-HD
158S-M-MD-HD
159S-HD
Replacement head mechanisms can be installed without
disturbing existing equalizing connections or disassembly
of components, making repair simple and easy.
INSTRUCTION MANUAL
MM-219J
Replacement Head Mechanism
WARNING
N
UTIO
A
C
G
NIN
R
A
W
•
• Before using this product read and understand instructions.
• Save these instructions for future reference.
• All work must be performed by qualified personnel trained in the proper application, installation, and maintenance of plumbing, steam, and electrical equipment and/or systems in
accordance with all applicable codes and ordinances.
• To prevent serious burns, the boiler must be cooled to 80˚F (27˚C) and the pressure must be
0 psi (0 bar) before servicing.
• To prevent electrical shock, turn off the electrical power before making electrical connections.
• This low water cut-off must be installed in series with all other limit and operating controls
installed on the boiler. After installation, check for proper operation of all of the limit and
operating controls, before leaving the site.
• We recommend that secondary (redundant) Low Water Cut-Off controls be installed on all
steam boilers with heat input greater than 400,000 BTU/hour or operating above 15 psi of
steam pressure. At least two controls should be connected in series with the burner control
circuit to provide safety redundancy protection should the boiler experience a low water
condition. Moreover, at each annual outage, the low water cut-offs should be dismantled,
inspected, cleaned, and checked for proper calibration and performance.
•
To prevent serious personal injury from steam blow down, connect a drain pipe to the control
opening to avoid exposure to steam discharge.
• To prevent a fire, do not use this low water cut-off to switch currents over 7.4A, 1/3 Hp at
120 VAC or 3.7A, 1/3 Hp at 240 VAC, unless a starter or relay is used in conjunction with it.
Failure to follow this warning could cause property damage, personal injury or death.
2
Enclosure rating: NEMA 1 General Purpose
Pump Circuit 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
Approximate
Distance Above
Cast Line Differential
Setting In. (mm) In. (mm)
Pump Off
15
/16 (24)
5
/16 (8)
Pump On
5
/8 (16)
Burner On
5
/8 (16)
3
/8 (16)
Burner Off
1
/4 (6.4)
Pump Off 13/8 (41)
3
/4 (19)
Pump On
5
/8 (16)
Burner On
7
/8 (22)
7
/8 (22)
Burner Off 0 (0)
BURNER OFF
BURNER ON
7
/8"
DIFFERENTIAL
(22mm)
PUMP
OFF
BURNER
OFF
NORMAL BOILER
WATER LINE
1
3
/8"
DIFFERENTIAL
(35mm)
PUMP OFF
PUMP ON
3
/4"
DIFFERENTIAL
(19mm)
PUMP OFF
PUMP ON
3
/4"
DIFFERENTIAL
(19mm)
PUMP
OFF
BURNER
OFF
NORMAL BOILER
WATER LINE
1
13
/16"
DIFFERENTIAL
(46mm)
OPERATION
Maximum Pressure: 150 psi (10.5 kg/cm2)
Electrical Ratings
Settings and Differential Pressures
Values are ± 8" (3.2mm).
Series 150S and 157S
150 psi (10.5 kg/cm
2
) Levels
150 psi (10.5 kg/cm
2
) Levels
0 psi
(0 kg/
cm2)
150 psi
(10.5 kg/
cm
2
)
Approximate
Distance Above
Cast Line Differential
Setting In. (mm) In. (mm)
Pump Off
15
/16 (24)
3
/8(16)
Pump On
9
/16 (14)
Burner Off 0 (0) N/A
Pump Off 17/16 (37)
3
/4(19)
Pump On 11/16 (17)
Burner Off - 3/8 (-16)
N/A
Model 150S-MD and 157S-MD
0 psi
(0 kg/
cm
2
)
150 psi
(10.5 kg/
cm
2
)
Pressure
Pressure
Alarm Circuit Rating
Voltage Amps
120 VAC 1
240 VAC 1/2
Motor Horsepower
Voltage Hp
120 VAC
1/3
240 VAC 1/3
3
Approximate
Distance Above
Cast Line Differential
Setting In. (mm) In. (mm)
Motorized
15
/16 (24)
Valve Closed
5
/16 (8)
Motorized
5
/8 (16)
Valve Open
Burner On
5
/8 (16)
3
/8(16)
Burner Off
1
/4 (6.4)
Motorized 13/8 (41)
3
/4 (19)
Valve Closed
Motorized
5
/8 (16)
Valve Open
Burner On
7
/8 (22)
7
/8(22)
Burner Off 0 (0)
BURNER OFF
BURNER ON
7
/8"
DIFFERENTIAL
(22mm)
MOTORIZED
VALV E
CLOSED
BURNER
OFF
NORMAL BOILER
WATER LINE
1
3
/8"
DIFFERENTIAL
(35mm)
MOTORIZED
VALV E
CLOSED
MOTORIZED
VALV E
OPEN
3
/4"
DIFFERENTIAL
(19mm)
Values are ± 8" (3.2mm).
NOTE: Due to the slower operation of some
motorized valves, complete valve opening
or closing will occur at slightly different
levels than indicated above.
Model 158S
150 psi (10.5 kg/cm
2
) Levels
0 psi
(0 kg/
cm
2
)
150 psi
(10.5 kg/
cm
2
)
Pressure
Settings and Differential Pressures (continued)
150 psi
(10.5 kg/
cm
2
)
MOTORIZED
VALVE
OPEN
CLOSED
3
/4"
DIFFERENTIAL
(19mm)
MOTORIZED
VALV E
CLOSED
BURNER
OFF
NORMAL BOILER
WATER LINE
1
13
/16"
DIFFERENTIAL
(46mm)
Approximate
Distance Above
Cast Line Differential
Setting In. (mm) In. (mm)
Pump Off
15
/16 (24)
3
/8(16)
Pump On
9
/16 (14)
Burner Off 0 (0) N/A
Pump Off 17/16 (37)
3
/4(19)
Pump On 11/16 (17)
Burner Off - 3/8 (-16)
N/A
Model 158S-MD
0 psi
(0 kg/
cm
2
)
Pressure
150 psi (10.5 kg/cm2) Levels
NOTE: Due to the slower operation of some
motorized valves, complete valve opening
or closing will occur at slightly different
levels than indicated above.
4
PUMP #1
OFF
PUMP #1
ON
NORMAL BOILER
WATER LINE
(19mm)
3
/4"
DIFFERENTIAL
PUMP #2 ON
AT CAST LINE
7
/8"
DIFFERENTIAL
(22mm)
PUMP #2
ON
PUMP #2
OFF
PUMP #1
OFF
PUMP #2
ON
PUMP #2 ON
AT CAST LINE
NORMAL BOILER
WATER LINE
1
3
/8"
DIFFERENTIAL
(35mm)
Values are ± 8" (3.2mm).
150 psi (10.5 kg/cm2) Levels
Approximate
Distance Above
Cast Line Differential
Setting In. (mm) In. (mm)
Pump #1 Off15/16 (24)
5
/16(8)
Pump #1 On5/8 (16)
Pump #2 Off5/8 (16)
3
/8(16)
Pump #2 On1/4 (6.4)
Pump #1 Off 13/8 (41)
3
/4(19)
Pump #1 On5/8 (16)
Pump #2 Off7/8 (22)
7
/8(22)
Pump #2 On
0 (0)
Model 159S
0 psi
(0 kg/
cm
2
)
150 psi
(10.5 kg/
cm
2
)
Pressure
Settings and Differential Pressures (continued)
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