Xylem MM 711B User Manual

Series 150, 150S, 157, 157S

!

Bellows Replacement

INSTRUCTION MANUAL

MM-711B

Series 150S

Series 150

WARNING

CAUTION

WARNING

• Before using 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 electrical shock, turn off the electrical power before making electrical
connections.

• To prevent serious burns release all pressure and let boiler cool down to 80˚F (27˚C).

• Drain water level down below the float bowl chamber before taking the head mechanism
out of the body.

Failure to follow this warning could cause property damage, personal injury or death.

C

E

D

A

L

F

J

K

B

M

H

D

H

G

J

K

B

C

J

F

A

G

D

P

N

R

E

OFF

ON

STEP 1 - Preparation

E

D

A

F

C

B

a. To prevent electrical shock turn off all electrical

power to the boiler.
CAUTION: There may be more than one source
of power to the boiler.

b. Release all pressure from the boiler and let it cool down to 80˚F (27˚C). Drain the water level

down below the float chamber.

c. Remove the four screws that hold the cover on the

switch housing (A) and remove the cover. Mark all
electrical supply wires so they can be returned to
the proper terminals. Remove the wires and conduit
connections from switch housing (A).

d. Remove eight hex head bolts holding head

mechanism (B) to float chamber. Carefully remove
head mechanism (B) from float chamber and place
in a vise.

e. Holding float (C) firmly, unscrew Allen

®

or Torx

®

fastener (D). (Units with date codes of E99 or earlier
will have Allen
F99 or later will have Torx

®

head fasteners. Those with codes of

®

fastener). Unscrew float
and float rod (C). For snap switch units see Step 3a.
For mercury switch units remove the two mercury
switches. Remove six (6) Allen

®

or Torx®screws (E).

f. Remove switch housing (A) from head casting (B).

The bellows assembly (F) may stick to the switch
housing (A). Remove bellow assembly (F) and
clean gasket surfaces on both head casting (B) and
switch housing (A).

Four Cover
Screws

A

B

Eight Hex
Head Bolts

2