Frymaster H55 Series Technical Reference Manual page 24

High-Effi ciency Gas
How High-Effi ciency Fryers Work
Sealed-burner fryers — 30 or 50 lb frypots — operate the same. Gas and air, pushed by a blower,
are delivered to a sealed burner and ignited. A series of events, before and after the ignition, en-
sure the successful operation of the fryer.
How it happens:
• Line voltage is supplied to 12 and 24-volt transformers. The 12 VAC goes to the controller
where it becomes 12VDC.
• 24VAC is provided to the ignition circuit, which fl ows through the drain safety switch and the
hi-limit.
• The controller's 12VDC fl ows to the interface board and powers the heat relay.
• When the temp probe, monitored by the controller, detects low temperature, the controller calls
for heat.
• The heat relay closes and pulls in the 24VAC for the spark modules and the line voltage for the
blower.
• The spark module provides 24VAC to the gas valve, power for the spark and at the same time
checks for presence of fl ame in the burner. If the fl ame is there, the gas valve stays open.
What can go wrong:
• Failed 12VAC transformer, no power to the controller.
• Failed 24VAC transformer, no power to the spark module or gas valve.
• Failed controller, no 12VDC power out to the heat relay: no power to the spark module and
nothing to the gas valve.
• LED's on the interface board indicate power for the controller and can be used as a guide.
• A failed heat relay on the interface board means no power to the spark module and, because it
works a double pole-double throw switch, no power to the blower.
• An open hi-limit prevents power from reaching the spark module circuit.
• Popping occurs when the ignition is delayed.
• The spark module uses fl ame rectifi cation (explained on page 2-14) to prove the presence of fi re
in the burner chamber. If no fl ame is sensed, the gas valve is denied power; the valve closes and
an alarm circuit is energized.
Simplifi ed versions of the electrical circuits for fryers with a single or two spark modules are
shown on the following page.
Troubleshooting
• LED's light up on the interface board along the path of the power, which can indicate where,
down stream, the problem with the fryer begins.
2-19