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GT INSTALLATION AND OPERATION INSTRUCTIONSPage 36
1. Check to see if water is dripping on the
sensor.
2. Reduce the Hi setting (and/or) ensure
that there is proper water circulation in
the system.
Check wiring
Check wiring. (Note: ER3 will be
displayed if temperature sensed is
less then 32°F, 0°C.)
Note: If problem is corrected by resetting
power, Sentry control had locked-up;
contact Smith.
1. Not enough fl ow to keep boiler from
tripping on limit. Verify that a min. of
6 GPM, 0.4 L/s, fl ow is going through
boiler & indirect circuit.
2. Reduce indirect Aquastat setting,
or Increase difference between (Lo
Setting) and (indirect Aquastat setting).
3. Indirect limit or wiring failure.
1. There is a problem in the ignition
sequence; it could be caused by a
faulty igniter, fl ame sensor, gas valve or
improper line pressure or combustion.
Check ignition sequence to determine
which component is not functioning.
(Sentry will retry ignition sequence
1 hour after ER6 code originally
occurs or if control is reset)
2. Check for 24V between B on terminal
block and F1 on Sentry plug, if not
present a limit has tripped (see wiring
diagram).
3. the Flow Switch on the GT-400 is also
in the 24V circuit. Check for proper
water fl ow and fl ow switch operation.
If OD probe is being used, the HI setting will
be calculated using formula in Section 8.
1. If the thermostat demand light is
turning off, the thermostat has satisfi ed.
2. If DHW temp light is turning off; the
aquastat or call for domestic has been
satisfi ed.
TROUBLE SHOOTING
This section is intended to assist the service technician in detecting and correcting common errors. The Sentry 2100
is equipped with an internal diagnostic system that verifi es control operation. The following series of error codes has
been developed to aid in diagnosing control problems:
Problem Detected Problem Solution
ER1 On Display
ER2 On Display
ER3 On Display
ER5 On Display
DHW Problem
ER6
Burner shuts off
before set-point
temperature is
reached (and burner
light goes out)
The Safety High Limit of 215°F, 102°C,
has been reached.
Water Probe... The water probe is
transmitting an invalid signal - closed
circuit.
Water probe...Sentry is sensing an open
circuit at water probe. Or, the wiring to the
outdoor probe is grounded.
The control has determined an Indirect
water heater problem; the boiler has
cycled off 10 times during a single call
for domestic. The Indirect call will now be
ignored until power is reset or the indirect
call is interrupted.
“Flame Lock Out”
Sentry has sensed a lack of 24V to the
gas valve during operation or a Fenwal
ignition lockout.
Reset calculation being used to
lower HI setting.
Thermostat is satisfi ed