Sterling QVSD User Manual
Page 27
27
Table 9 - Troubleshooting Guide
SYMPTOMS
POSSIBLE CAUSE(S)
CORRECTIVE ACTION
1. Loose
wiring.
2. Defective motor overload
protector or defective motor.
3. Defective power ventor relay.
1. Fan relay heater element
improperly
wired.
2. Defective ventor relay switch.
3. Motor protector cycling on and off.
4. Motor not properly oiled.
1. Improperly wired ventor relay.
2. Main burners not lighting while
thermostat calls for heat.
3. Defective ventor relay.
1. Incorrect gas input.
2. Heater
undersized.
3. Thermostat
malfunction.
4. Heater cycling on high limit.
5. Check outside dampers if used.
1. Thermostat
malfunction.
2. Heater runs continuously.
1. Fan relay heater element
improperly
wired.
1. Check and tighten all wiring
connections per diagrams.
Thermostat wires tagged “W” and
“G” must be connected together
(unless special thermostats are
used; if so, see thermostat wiring
diagram). See “Electrical
Connections”.
2. Replace
motor.
3. Check 24V across 1 and 3
terminals on fan relay. If 24V is
present, jumper terminals
numbered 2 and 4. If motor runs,
the relay is defective and must be
replaced. If 24V in not present,
check wiring per wiring diagrams.
1. Be sure ventor relay heater
terminals are connected per
diagrams.
2. Replace ventor motor.
3. Check motor amps against motor
name plate rating, check voltage,
replace power ventor motor if
defective.
4. Refer to label on motor.
1. Check all wiring.
2. Refer to H & N Symptoms.
3. Replace ventor relay.
1. Refer
to
“Operation”.
2. This is especially true when
heated space is enlarged. Have
heat loss calculated and compare
to heater output (80% of input).
Your gas supplier or installer can
furnish this information. If heater is
undersized, add additional heaters.
3. Replace
thermostat.
4. Check air movement through heat
exchanger. Check voltage to fan
motor. Clean power ventor motor.
5. Adjust dampers accordingly.
1. Replace
thermostat.
2. Check wiring diagrams; Check
operation at valve. Look for short
(such as staples piercing thermo-
stat wiring) and correct: Replace
gas valve; Refer to “Operation”.
1. Be sure fan relay heater terminal
are connected per diagrams.
O. Power ventor will not run.
P. Power ventor motor turns
on and off while burners
are
operating.
Q. Power ventor motor will
not
stop.
R. Not enough heat.
T. Too much heat.
U. Cold air is delivered on
start-up