Xylem MM 244B Series 42S Replacement Snap Switch Assembly - Manual (Page 10)

10
RULER
CAST
LINE
LEVEL
3" (76.2mm) 2" (50.8mm) 1" (25.4mm) Casting
Cut-Off
Line
1" (25.4mm)
TOP
SECTION 3 - Checking Switch Settings at 0 Pressure
2. Hold the ruler against the side of the gauge glass
in a position so the Cast Line mark is on the same
level as the cast line on the float chamber of the
control (a carpenter's level should be used to
insure the cast line on the float chamber is on the
same plane as the one on the marker).
3. Once the marker is properly positioned, tape it to
the gauge glass.
PUMP OFF
PUMP ON
BURNER
CUT-OFF LEVEL
AT CAST LINE
4a. Drain the water level in the boiler until the pump
turns on. Note the level at which the pump turns on
and then turns off. Verify that pump settings are
acceptable.
b. Turn the pump off.
BURNER
ON
BURNER
OFF
NORMAL BOILER
WATER LINE
BURNER
CUT-OFF LEVEL
AT CAST LINE
7/8 " (22mm)
5a. Drain the water level in the boiler until the burner turns
off. Observe the burner off point.
b. Turn the pump back on and observe the Burner On
point as the boiler fills with water. In the case of manual
reset models, try resetting the burner switch as close as
possible to the Burner On point as shown in chart for
the control and as measured on the switch level ruler.
Verify that burner settings are acceptable.
2"
(50.8mm)
1"
(25.4mm)
1"
(25.4mm)
3"
(76.2mm)
Casting
Cut-Off
Line
1. Find the "Switching Level Ruler" on page 11,
and cut it out along the indicated lines.
(Not to Scale. Template
located on page 11).
IMPORTANT: All switches have fixed differentials. Adjustment of switches referred to in Sections 2 and 3 are
all based upon Pump Off and Burner Off setpoints. The Pump On and Burner On setpoints are not adjustable.