Trane S*HF*20-75 Troubleshooting Manual page 127

Table 11: Diagnostics Troubleshooting Chart (continued)
Heat Failure
Module: HEAT
Heat Module
Communication Failure
Module: HEAT
RT-SVP07B-EN
Problem: The Gas or
Electric heat controls has
failed or has marginal
performance and the Heat
Fail Input has closed:
a. for more than 80
seconds,
b. for 10 consecutive
occurrences (each lasting 5
seconds or more) within a
210 second period.
(This is typically caused
when the gas heater's
igniter failed to light the
gas, or because the electric
heat section became too
hot.)
Check Gas Heat: External
ignition controller, wiring,
combustion fan motor and
airflow operation, etc.
Check Electric Heat:
Wiring, sufficient airflow,
etc.
Problem: The RTM has lost
communications with the
HEAT module.
Check: Check unit wiring
between RTM and HEAT
module.
An Information Only
diagnostic is set.
An "All Heat Off" request is
sent to the heat operation
function:
a. On staged gas or electric
heat units, all heat module
outputs will be de-
energized.
b. On hydronic heat or
chilled water units, the
supply fan will be turned
off, the outside air damper
closed, hydronic/chill water
valves will be driven to
100%, and the relay
outputs will be controlled
for proper signal routing to
actuators.
DIAGNOSTICS Menu
(INFO) An automatic reset
occurs after the Heat Fail
input remains open for 210
seconds continuously.
(PAR) An automatic reset
occurs after
communication has been
restored.
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