Xylem MM 705D No. 11, 11M and 11MV Replacement Switch for use on Series 61, 64, 764, 67, 767, 69 and 70 Low Water Cut-Offs - Manual (Page 4)

Xylem Inc.
8200 N. Austin Avenue
Morton Grove, Illinois 60053
Phone: (847) 966-3700
Fax: (847) 965-8379
www.xyleminc.com/brands/mcdonnellmiller
McDonnell & Miller is a trademark of Xylem Inc. or one of its subsidiaries.
MAINTENANCE
SCHEDULE:
• Blow down weekly during heating season.
• Check all wiring for brittle or worn insulation.
Replace control every 10 years.
TROUBLESHOOTING
Problem:
1. Control does not turn burner off on low water.
2. Control does not turn electric feeder off.
Cause: Contacts may be fused from overload.
Test: With a continuity meter or ohm meter check if both
circuits open as the rocker is moved through its operating
range.
Solution: Replace the switch if either circuit remains closed
through the test. Refer to the installation / replacement
procedure.
If the switch functions normally off of the control, inspect the float and
interior chamber condition for obstructions and debris, especially
around the bellows area and at the gauge glass end.
Follow ASME Boiler and Pressure
Vessel Code - Section VI Paragraph
7.07G.
It states that the controls
should be dismantled annually by
qualified personnel, to the extent
necessary to insure freedom from
obstructions and proper functioning of
the working parts.
© 2013 Xylem Inc. MM-705D July 2013 Part No. 246702