90
Direct-Fired Make-up Air •
MUA-SVX01A-EN
Trouble Shooting
Incorrect space
temperature calibration.
Follow procedures
outlined in
a. If proper
action is
obtained, first
check room
sensor/
selector.
Recalibrate if
necessary.
Open circuit in room
sensor/selector.
Measure resistance across
room sensor/selector.
a. If reading is
incorrect,
replace room
temperature
sensor/room
temperature
selector or
repair wiring.
12. Incorrect space
temperature.
Incorrect maximum
discharge air
temperature setting at
amplifier.
Check to see if heater is
delivering air at maximum
discharge air setting.
a. If desired
temperature is
not reached,
increase
maximum
discharge air
temperature
setting.
Incorrect minimum
discharge air
temperature setting at
amplifier.
Check to see if heater is
delivering air at minimum
discharge air setting.
a. If desired
temperature is
not reached,
decrease
minimum
discharge air
temperature
setting.
Insufficient burner
capacity.
Check to see if heater is
operating at high fire.
a. If desired
space
temperature is
not reached
with heater at
high fire, it
may be
undersized.
Consult
factory.
Incorrect space
temperature calibration.
Place thermometer next
to room sensor/selector
or room temperature
sensor. Compare space
temperature reading with
room sensor/selector or
room temperature sensor
dial setting.
a. If
temperature
reading is
incorrect,
check all items
listed in
symptom 12,
then
recalibrate if
necessary.
Table 18.
Trouble shooting guide for Modulationg Room Temperature (MRT)
controls
Symptom
Probable Cause
Field Test
Solution
*
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.
