Xylem MM 414B User Manual

Series 150E and 157E

Low Water Cut-Off/Pump Controllers

For Steam Boilers and Other Level Control Applications

Typical Applications:
– Primary or secondary pump controller/

low water fuel cut-off

for steam boilers
– Motorized valve controller
– Low water and high water cut-off
– Dual pump control
– Alarm actuator

A

B

• 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 16A, 1 Hp at
120 VAC or 8A, 1 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.

WARNING

CAUTION

!

WARNING

Series 150E

Series 157E

®

with

MERCURY
FREE

1 HP
Relays

U.S. Pat. No. 6,571,625

McDonnell & Miller

Installation & Maintenance

Instructions

MM-414(B)

SPECIFICATIONS

Maximum Pressure: 150 psi (10.5 kg/cm2)

2

FEATURES

Burner Delay (DOB): 0 to 60 seconds (Field Adjustable)

Ambient Temp: 120˚F Max.

NOTE: The circuit board is protected with a sensor which will
shut down the unit if the temperature at the board exceeds
176˚F (80˚C). The board will reset when the temperature at
the board drops below 167˚F (75˚C).

Burner Relay Time Delay

There is a field-adjustable time delay (DOB) to
prevent nuisance burner shut-down. The number
of seconds water needs to be off the bottom probe
before the burner relay is deactivated can be set
between 0 and 60 seconds.

Redundant Low Water Cut-Off

When the boiler water drops below the middle
probe, a 3 minute timing circuit will be activated. If
water does not return to the middle probe within
three minutes, the burner relay will deactivate. The
Red LED will flash once every second if this
condition occurs.

•Automatic Reset units will automatically reset
when the water level is restored to the middle
probe.

• The reset button on Manual Reset units will
have to be pressed after water is restored to
the middle probe.

NOTE: The timing circuit will automatically reset
if the water level is restored to the middle probe
within 3 minutes.

Redundant Pump Off

The pump relay will be activated after water drops
below the middle probe. If the water level is not
restored to the top probe within 3 minutes the pump
relay will be deactivated. After the pump relay is
deactivated, normal operation is resumed. Water
must again drop off the middle probe to activate the
pump relay. There is no LED signal for this
occurance.

CSD-1 Code Compliance

On Manual Reset units, if the control is in a low
water condition (burner relay deactivated) prior to
an interruption of power, the control will remain in a
low water condition when power is restored. The
reset button will need to be pressed when the water
level again covers the middle probe.

Adjustable Pump Differentials

ELECTRICAL RATINGS & SWITCH RATINGS

Supply Probe Full Load (Amps) Locked Rotor (Amps) Pilot Duty (VA) Motor (HP)
Voltage Voltage NO (NC), VAC NO (NC), VAC NO (NC), VAC NO (NC), VAC

120 VAC 5 VAC 16 (5.8), 120 96 (34.8), 120 470 (290), 120 1 (1/4), 120
50/60 HZ maximum 8 (2.9), 240 48 (17.4), 240 470 (290), 240 1 (1/4), 240

3

BURNER

CUT-OFF LEVEL

AT CAST LINE

(22mm)

BURNER OFF

BURNER ON

7

/8"

PUMP

OFF

BURNER

OFF

BURNER

CUT-OFF LEVEL

AT CAST LINE

2

1

/16"

(52 mm)

NORMAL BOILER

WATER LINE

1

3

/16"

(30 mm)

PUMP OFF

PUMP ON

NORMAL BOILER

WATER LINE

When the water level in the boiler drops below the
middle probe, the circuit is broken which will acti­vate the pump relay. When the water level rises
above the top probe, the circuit is made and the
pump relay is deactivated.

The distance between the top and middle probes is
adjustable. By turning the flange one bolt hole
clockwise, the distance can be increased by 7/16”.

When the water level in the boiler drops below the
bottom probe, the circuit is broken which will deacti­vate the burner relay. When the water level is
restored to the middle probe, the burner relay will
be activated for auto reset controls only.

SWITCH SETTINGS:

Values are ±

3

/16” (6mm).

Flange in “B” PositionFlange in “A” Position

Burner Off has adjustable 0-60 second time delay.

Approximate

Distance Above

Cast Line Differential

Setting In. (mm) In. (mm)

Pump Off 1

5

/8 (41)

3

/4 (19)

Pump On

7

/8 (22)

Burner On

7

/8 (22)

7

/8 (22)

Burner Off 0 (0)

BURNER

CUT-OFF LEVEL

AT CAST LINE

(22mm)

BURNER OFF

BURNER ON

7

/8"

PUMP

OFF

BURNER

OFF

BURNER

CUT-OFF LEVEL

AT CAST LINE

1

5

/8"

(41mm)

NORMAL BOILER

WATER LINE

3

/4" (19 mm)

PUMP OFF

PUMP ON

NORMAL BOILER

WATER LINE

Burner Off has adjustable 0-60 second time delay.

Approximate

Distance Above

Cast Line Differential

Setting In. (mm) In. (mm)

Pump Off 2

1

/16 (52)

13/16(30)

Pump On

7

/8 (22)

Burner On

7

/8 (22)

7

/8(22)

Burner Off 0 (0)

4

If the control will be the primary low
water fuel cut-off, size the steam (top)

and water (bottom) equalizing pipe lengths
so that the horizontal cast line on the body
is 1

3

/8” (35mm) below the boiler’s normal
water level, but not lower than the
lowest safe permissible water level, as
determined by the boiler manufacturer.

OR

If the control will be the secondary low
water fuel cut-off, size the steam (top) and

water (bottom) equalizing pipe lengths so
that the horizontal cast line on the body is

at or above, the lowest safe permissible
water level, as determined by the boiler
manufacturer.

STEP 1 - Determine the Elevation at Which the
Low Water Cut-Off/Pump Controller Must be Installed

INSTALLATION –

TOOLS NEEDED:

Tw o (2) pipe wrenches, one (1) flatblade screw­driver, and pipe sealing compound.

IMPORTANT: Follow the boiler manufacturer's
instructions along with all applicable codes and
ordinances for piping, blow down valve and water
gauge glass requirements.

13/8"

STEAM EQUALIZING PIPE

VERTICAL EQUALIZING PIPE

NORMAL BOILER WATER LINE

AS A PRIMARY
LOW WATER CUT-OFF/PUMP
CONTROLLER

BURNER CUT-OFF LEVEL AT CAST LINE

LOWEST
PERMISSIBLE
WATER LEVEL

(35mm)

WATER

EQUALIZING

PIPE

BLOW DOWN VALVE

BLOW DOWN VALVE

STEAM EQUALIZING PIPE

VERTICAL EQUALIZING PIPE

BLOW DOWN VALVE

BURNER CUT-OFF LEVEL AT CAST LINE

LOWEST
PERMISSIBLE
WATER LEVEL

BURNER OFF

WATER

EQUALIZING

PIPE

AS A SECONDARY
LOW WATER CUT-OFF/PUMP
CONTROLLER

BLOW DOWN VALVE

b. Install a water gauge glass (J).

Note: Gauge glass and tri-cocks

not included with product.

J

5

F

E

D

a. Mount and pipe the low water cut-off (D) on a

vertical equalizing pipe (E) at the required ele­vation level, as determined in Step 1.

Install blow down valves directly below the
lower cross of the water equalizing pipe (F).

STEP 2 - Installing the Low Water Cut-Off

J

H

a. Install a water column (H) (not included with

product) for all models except Series 157E,
(with integral water column).

STEP 3 - Installing a Water Gauge Glass (Required on all steam boilers)

Series 157E

All Other Models

GAUGE GLASS

(TYPICAL)

TRI-COCK
(TYPICAL)