Xylem MM 235E Replacement Snap Switch Assembly SWA 150S 150S MD 158S 159S - Manual (Page 8)

8
INSTALLATION
SECTION 2 - Checking Switch Settings and Adjusting Switch Setpoints at
Operating Pressure
IMPORTANT: All switches have fixed differentials.
Adjustment of switches referred to in Step 2 and 3
are all based upon Pump Off and Burner Off set-
points. The Pump On and Burner On setpoints are
not adjustable. We strongly recommend that you check the con-
trol at both the operating pressure and at 0 pres-
sure. All boilers start at 0 psi regardless of the oper-
ating pressure.
The operating points will spread out as the pressure
goes up and shrink as the pressure goes down.
1. Cut out the "Switching Level Ruler" (page 5)
along the indicated lines.
RULER
I
LEVEL
2a. 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 (I) (a carpenter's level should
be used to insure the cast line on the float chamber is
at the same level as the one on the ruler).
b. Once the ruler is properly positioned, tape it to the gauge glass.
3a. Bring boiler up to normal operating pressure and turn the
pump off.
b. Remove the cover (J).
J
(Not to Scale. Template
located on page 5).
2"
(50.8mm)
1"
(25.4mm)
1"
(25.4mm)
3"
(76.2mm)
Casting
Cut-Off
Line