Improper Temperature Control - Frymaster 47 Series Service & Parts Manual

47 SERIES GAS FRYERS
CHAPTER 1: SERVICE PROCEDURES
1.9.2 Improper Burner Functioning (cont.)
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 incoming 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 air conditioning/ventilation units start and stop, the pressure in the
kitchen may change from positive or neutral to negative, or vice versa. Changes in airflow patterns
that may affect flame intensity are caused by these variations.
Flames "rolling" out of the fryer are usually an indication of negative pressure in the kitchen. Air is
being sucked out of the fryer enclosure and the flames are literally following the air. If negative
pressure is not the cause, check for high burner-manifold gas pressure in accordance with the
procedures in Section 1.4. An obstructed flue, which prevents the fryer from properly exhausting,
may also be the cause.
An excessively noisy burner, especially with flames visible above the flue opening, may indicate
that the burner gas pressure is too high, or it may simply be that the gas valve vent-tube is blocked.
If the gas pressure is correct and the vent-tube in unobstructed, the gas valve regulator is probably
defective.
Occasionally a burner may apparently be operating correctly, but nevertheless the fryer has a slow
recovery rate [the length of time required for the fryer to increase the oil temperature from 250°F to
300°F (121°C to 149°C)]. Primary causes are low burner-manifold pressure and/or misaligned or
missing deflector targets. If both of these causes are ruled out, the probable cause is a misadjusted
gas-valve regulator. Refer to the Check Burner Manifold Pressure procedure in Section 1.4 if gas-
valve regulator is suspected of being out of adjustment.

1.9.3 Improper Temperature Control

Temperature control, including the melt cycle, is a function of several interrelated components, each
of which must operate correctly. The principal component is the thermostat (in thermostat control
units) or the temperature probe (in fryers equipped with other types of controllers). Depending
upon the specific configuration of the fryer, other components may include the interface board, the
controller itself, and the ignition module.
Improper temperature control problems can be categorized into melt cycle problems and failure to
control at setpoint problems.
Melt Cycle Problems
In fryers equipped with thermostat controls, a mechanical timer controls the melt cycle. There are
three components that may fail, thus disabling the melt cycle. The melt-cycle timer itself, the melt-
cycle timer microswitch, or the control panel melt-cycle ON/OFF switch. In all cases, the defective
component must be replaced.
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