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TROUBLESHOOTING GUIDETROUBLESHOOTING GUIDE
Series 14 Discharge Temperature Control
continued
Reproduced with permission from Maxitrol
®
Company
Symptom Possible Cause Field Test Remedy
1. Inlet Air sensor is
used.
2. Incorrect wiring.
3. System out of
calibration.
4. Improper TS114
location.
5. Room Override
Thermostat circuit
closed.
1. Short circuit in
modulator coil.
2. Short circuit between
amplifier and
modulator valve.
1. Override Temperature
setting is too low.
2. Burner capacity may
be insufficient.
1. Faulty automatic
control valve.
2. Open wire to
automatic valve.
1. Sensed temperature will
vary from TD114 dial
settings. This is intentional.
2. Correct wiring.
3. See calibration procedure.
4. Move TS114 to location
where average repre-
sentative temperature can
be sensed.
5. TD114 dial setting, then
check thermostat setting
and/or check wiring for
shorts.
1. Replace modulator head if
less than 40 ohms.
2. Correct wiring if short is
found.
1. Reset to correct
temperature.
2. If on high fire, control can
do no more. Heater unable
to furnish additional heat to
raise temperature.
1. Replace automatic control
valve.
2. Correct wiring.
I. Incorrect
Discharge Air
Temperature.
J. Burned out
Transformer.
K. Discharge Air
Temperature
too low when
T115 is
operative.
L. Automatic
Control Valve
will not open
despite full
range of mod-
ulating voltage
at terminals 3
& 4.
1. Inlet Air Sensor changes
1° for each 3.5°, 5° or 8°
outside temperature
change from 60° (predeter-
mined - turndown varies
with model used).
2. Check wiring diagram for
heater.
3. Sensed temperature
(thermometer next to
TS114) does not
correspond to TD114
setting.
4. Sensed temperature
(thermometer next to
TS114) does not represent
average discharge air
temperature.
5. Remove Override
Thermostat lead from
terminal 2 of TD114.
1. Measure resistance across
modulator terminals with
red lead wires discon-
nected.
2. Inspect wiring.
1. Check “Override Temper-
ature Selector” of TD114.
2. Check for high fire
(Maxitrol manifold pressure
specified for heater).
1. Read voltage across auto
valve terminals. If 24V AC,
valve is faulty.
2. Read voltage across
terminals 5 and 6. If 24V
AC, check for open circuit
to automatic valve.
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