Xylem MM 221G Models 157S RBP MD Low Water Cut-Offs/Pump Controllers - Manual (Page 3)

NORMAL BOILER WATER LINE
“CUT-OFF” LEVEL AT CAST LINE
1 1 /
2
"
(38mm)
MINIMUM
SAFE
WATER
LEVEL
BLOW DOWN VALVE
BLOW DOWN VALVE
Size the steam (top) and water (bottom)
horizontal equalizing pipe lengths so that
the horizontal cast line on the body is 1
2"
(38mm) below the boiler’s normal water
level, but not lower than the minimum
safe 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:
Two (2) pipe wrenches, one (1) flathead screw
driver, and pipe sealing compound.
3
IMPORTANT: Follow the boiler manufacturer's
instructions along with all applicable codes and
ordinances for piping, blow down valve and water
gauge glass requirements.
a. Using a pipe wrench, unscrew the plastic float
blocking plug (A) from the float block tapping
of the low water cut-off body (B).
Install pipe plug (provided) to seal port.
STEP 2 - Installing the Low Water Cut-Off
A
B
b. Mount and pipe the low water cut-off (C) on a
vertical equalizing pipe (D) at the required
elevation level, as determined in Step 1.
Install full ported blow down valves directly below
the lower cross of the water equalizing pipe (F).
NORMAL BOILER
WATER LINE
C
D
F
BLOW DOWN VALVE
BLOW DOWN VALVE
The plug must be reinstalled before control is
shipped installed on the boiler, and removed
when boiler is installed after shipment.
Failure to follow this caution may damage
float and operating mechanism
! CAUTION