Xylem MM 235E Replacement Snap Switch Assembly SWA 150S 150S MD 158S 159S - Manual (Page 11)

11
RULER
CAST
LINE
LEVEL
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
“CUT-OFF LEVEL”
AT CAST LINE
BURNER OFF
BURNER ON
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 reset-
ting 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.
1. Find the "Switching Level Ruler" on page 5,
and cut it out along the indicated lines.
(Not to Scale. Template
located on page 5).
IMPORTANT: All switches have fixed differentials. Adjustment of switches referred to in Sections 2 and
3 are based upon Pump Off and Burner Off setpoints. The Pump On and Burner On setpoints are not
adjustable.
IMPORTANT: Where Pump On/Off and Burner On/Off are referenced in these instructions, Pump #1 On/Off
and Pump #2 Off/On should be substituted, respectively, for a 159S control, and Motorized Valve
Open/Closed can substitute for Pump On/Off for a 158S control.
7. Turn the boiler on.
OFF
ON
6. Re-attach the junction box cover (P). J
INSTALLATION
SECTION 3 - Checking Switch Settings at 0 Pressure
2"
(50.8mm)
1"
(25.4mm)
1"
(25.4mm)
3"
(76.2mm)
Casting
Cut-Off
Line
NOTE
Manual reset units with date codes of 03K and newer require the cover to
be installed for proper operation of the manual reset mechanism.
Note:
Cover must be installed correctly as shown