Bunn Dual SH Installation And Operating Manual page 43

TROUBLESHOOTING (cont.)
Problem
Water will not heat or display shows
HEATING TIME TOO LONG (cont.)
Spitting or unusual steaming from
sprayhead or air vents. (Water too
hot)
Possible Cause
3. Triac
4. Electronic Control Board
1. Triac
2. Lime Buildup
CAUTION - Tank and tank compo-
nents should be delimed regularly
depending on local water conditions.
Excessive mineral buildup on stain-
less steel surfaces can initiate cor-
rosive reactions resulting in serious
leaks.
Page 43
Troubleshooting Procedures
Remove power from the brewer.
Connect a voltmeter across one of
the tank heaters. Reapply power to
the brewer and refer to Testing Indi-
vidual Components on page 33. If
the full supply voltage is measured
when the tank heater is turned on,
and zero voltage is measured with
the triac off, then the triac is good. If
half the supply voltage is measured,
the triac is defective. If very low, or
zero voltage is measured, there could
be a defective triac or a defective
control board.
Perform the above procedure for
testing triacs. If the voltage mea-
sured is very low or zero, then sub-
stitute a control board known to be
in good working order.
Remove power from the brewer.
Connect a voltmeter across one of
the tank heaters. Reapply power to
the brewer and refer to Testing Indi-
vidual Components on page 33. If
the full supply voltage is measured
when the tank heater is turned on,
and zero voltage is measured with
the triac off, then the triac is good. If
half the supply voltage is measured,
the triac is defective. If very low, or
zero voltage is measured, there could
be a defective triac or a defective
control board.
Inspect the tank assembly for ex-
cessive lime deposits. Delime as
required.
29877 091201