Applied Air GAS-FIRED HEATERS, Installation & Operation Instruction

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1. Readjust linkage on valve or
replace if necessary.
1. If readings are incorrect,
replace Outside or Inlet Air
Temperature Sensor (TS-01)
or Discharge Air Temperature
Sensor (TS-03) or repair
wiring.
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 Sequence and Burner
Setup in Section X.
1. If readings are incorrect,
replace Discharge Air
Temperature Sensor
(TS-03) or repair wiring.
2. If desired temperature is
not reached, increase
Maximum Heating Discharge
Temperature Setpoint.
1. If desired Space
Temperature is not reached,
increase Minimum Heating
Discharge Setpoint.
2a. Change to correct setpoint.
2b. Change to correct setpoint.
3. If desired Space Temper-
ature is not reached with
heater at high fi re, it may be
undersized. Consult Factory.
SECTION VII - TROUBLESHOOTING WITH DDC CONTROLS
continued
Modulating Room Temperature (MRT, MRT-PRO or MRT-EXPERT) Controls continued
Symptom Possible Cause Field Test Remedy
1. Foreign object holding
butterfl y valve (GP-39)
open.
1. Open circuit in Outside
or Inlet Air Temperature
Sensor (TS-01) and
Discharge Air Temperature
Sensor (TS-03)
1. Inlet pressure too low.
2. Incorrect outlet
pressure adjustment.
1. Open circuit in Discharge
Air Temperature Sensor
(TS-03).
2. Incorrect Maximum
Heating Discharge
Temperature Setpoint.
1. Incorrect Minimum Heating
Discharge Temperature
Setpoint.
2. Incorrect space setpoint.
3. Insuffi cient burner capacity.
G. Continuous High
Fire (Electronics
OK).
H. Continuous High
Fire (Electronics
Problem).
I. Incorrect High
Fire.
J. Continuous
Maximum
Discharge Air
Temperature.
K. Incorrect Space
Temperature.
Control circuits external to MRT Controls can cause burner malfunction.
Always check manual valve to be certain gas is on, and check limit controls for normal operation.
1. Inspect linkage valve.
1. Measure resistance per
Thermistor Curve.
1. Read inlet pressure at
valve, using a manometer
with heater operating at full
fi re. Pressure should be at
least equal to the sum of:
outlet pressure setting and
pressure drop of the valve.
2. Read outlet pressure using
manometer and compare
with the pressure stated on
the specifi cation plate.
1. Measure resistance per
Thermistor Curve.
2. Check to see if heater is
delivering at Maximum
Heating Temperature
Discharge Setpoint.
1. Check to see if heater
is delivering at Minimum
Discharge Setpoint.
2a. Check Unit Enable
Potentiometer (MP-15)
Setpoint.
2b. Check Heating Occupied
and/or Unoccupied setpoint.
3. Check to see if heater is
operating at high fi re.
(Refer to Digital Control System User Manual for additional troubleshooting suggestions)