37
SERVICE
Problem Probable Cause Corrective Action
Follow these steps to troubleshoot a Robertshaw Valve:
1. Complete System check:
With thermostat
contacts closed and gas cock dial “ON”,
main burner should ignite. If not, measure
across TP and TH terminals. If the reading is
more than 100 MV, replace the gas valve.
2. System Resistance Check: With
thermostat
contacts closed and main burner “ON”,
measure the millivolt reading between THTP
and TH terminals. Reading should be less
than 80MV. If not, recheck thermostat leads
and connections. Replace with new or heavier
gauge wires if necessary. If the reading is
still greater than 80 MV, replace the thermostat.
3. Automatic Pilot Dropout Check:
With
thermostat contacts open, depress gas cock
knob with pilot lit until maximum millivolt
output is observed between terminals THTP
and TP. Extinguish the pilot and observe the
meter. The sound of the pilot magnet dropping
should be audible. The dropout should
occur between 120MV and 30MV. If outside
these limits, change the gas valve.
Improper Burner Functioning
The
burner lighting on one side only
may be caused by a missing or misaligned rear deflec-
tor target or improper burner manifold pressure. Clogged burner orifices are usually the cause
of
gaps in burner firing
.
Fluctuating flame intensity
is normally caused by either improper or fluctuating incoming
gas pressure, but may also be the result of variations in the kitchen atmosphere. Verify incom-
ing gas pressure in the same way as for “popping,” discussed in the preceding paragraphs.
Variations in the kitchen atmosphere are usually caused by air conditioning and/or ventilation
units starting and stopping during the day. As they start and stop, the pressure in the kitchen
may change from positive or neutral to negative, or vice versa. They may also cause changes
in airflow patterns that may affect flame intensity.
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Содержание Legend RD18
Страница 42: ...40 SERVICE...
