Xylem MM 200G Series 64 Low water Cut-Offs - Manual (Page 8)

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.
• Open up float chamber and clean annually.
More frequent cleaning may be necessary if
there are high make-up water requirements or
poor local water quality.
• Replace control every 10 years.
TROUBLESHOOTING
Problem:
1. Burner does not shut off on low water.
a. Cause: Float chamber is loaded with mud or
sediment.
Test: With water level below the control
check if terminals 1 and 2 are open. If
not, remove switch and manually test if
terminals 1 and 2 can be opened.
Solution: Open float chamber and clean. At this
time, check for a build-up of scale or
sediment between corrugations of the
bellows.
b. Cause: Contacts are fused together.
Test: Remove switch and operate manually to
verify proper switch operation.
Solution: Replace switch. Check electrical load
and make sure it is within the ratings of
the switch.
2. Electric water feeder does not shut off.
a. Cause: Build-up of scale or sediment between
corrugations of the bellows.
Test: With water level above the control,
check if terminals 3 and 4 are open. If
not, remove switch and manually test
to verify terminals 3 and 4 can be
opened.
Solution: Open float chamber and replace or
clean the bellows.
b. Cause: Contacts are fused together.
Test: Remove switch and operate manually
to verify proper switch operation.
Solution: Replace switch. Check electrical load
and make sure it is within the ratings of
the switch.
© 2013 Xylem Inc. MM-200G July 2013 Part No. 245632