Xylem MM 206F Series 63 Low Water Cut-Off - Manual (Page 6)

6
TROUBLESHOOTING
TESTING
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 C and N.C. are open.
If not, remove switch and manually test
if terminals C and N.C. 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.
CUT OFF
LEVEL
TEST
OPENING
• Control can be tested on a hot water
boiler by gently inserting a screwdriver
or similar tool in the test opening below
the switch (see drawing) and lifting linkage
to cause float to drop, thereby simulating a
low water condition.