Sterling SDFI, Installation And Maintenance Instructions Manual

Page: 26 / 36

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TROUBLESHOOTING GUIDE TROUBLESHOOTING GUIDE
Series 44 Room Temperature Control continued
Reproduced with permission from Maxitrol ® Company
Symptom Possible Cause Field Test Remedy
1. Read inlet pressure at
valve, using a manometer
with heater operating at full
fire. Pressure should be at
least equal to the sum of:
outlet pressure setting and
pressure drop of the valve
plus 1.0" w.c.
2. Read outlet pressure using
manometer and compare
with the pressure stated on
the specification plate.
1. Follow procedures outlined
in “Preliminary Circuit
Analysis” in Section IX.
2. Measure resistance per
item E2.
3. Follow procedures outlined
in “Preliminary Circuit
Analysis” in Section IX.
1. Measure resistance per
item B1.
1. Check to see if heater is
delivering air at maximum
discharge air setting.
2. Check to see if heater is
delivering air at minimum
discharge air setting.
3. Check to see if heater is
operating at high fire.
4. Place thermometer next to
T244 or TS244. Compare
space temperature reading
with T244 or TD244 dial
setting.
1. Inlet pressure too low.
2. Incorrect outlet
pressure adjustment.
1. Faulty amplifier.
2. Open circuit in T244 or
TS244/TD244.
3. Incorrect space
temperature calibra-
tion.
1. Short in modulator coil
circuit.
1. Incorrect maximum
discharge air temper-
ature setting (A1044).
2. Incorrect minimum
discharge air temper-
ature setting (A1044).
3. Insufficient burner
capacity.
4. Incorrect space
temperature calibra-
tion.
I. Incorrect High
Fire.
J. Continuous
Maximum
Discharge Air
Temperature.
K. Burned out
Transformer.
No Voltage to
Amplifier.
L. Incorrect
Space
Temperature.
1. Increase inlet pressure if
possible or change to
larger valve. Consult
factory about possibility of
using special spring to
reduce pressure drop on
selected installations.
2. See Valve Adjustments -
Section IX.
1. If amplifier is proven at
fault, install replacement
amplifier.
2. If reading is incorrect,
replace T244, TS244/
TD244 or repair wiring.
3. If proper action is obtained,
first check item 22.
Recalibrate if necessary.
1. If proper resistances are
not observed, replace
modulator head or repair
wiring.
1. If desired temperature is
not reached, increase
maximum discharge air
temperature setting.
2. If desired space temper-
ature is not reached,
decrease minimum
discharge air temperature
setting.
3. If desired space temper-
ature is not reached with
heater at high fire, it may
be undersized. Consult
factory.
4. If temperature reading is
incorrect, check items 25,
26 & 27, then recalibrate if
necessary.
Control circuits external to Series 44 can cause burner malfunction.
Always check manual valve to be certain gas is on, and check limit controls for normal operation.