Frymaster FGP55 Series, Service & Parts Manual, Page: 5 / 50

FGP55 SERIES GAS RETHERMALIZERS
CHAPTER 1: SERVICE PROCEDURES
1-1
1.1 Functional Description
FGP55 Series gas rethermalizers contain a welded stainless steel cookpot that is heated by gas
flames diffused evenly through tubes built into the cookpot.
Flames originate from orifices in a burner manifold positioned beneath the burners. The burners are
positioned in the tube openings, at the front of the cookpot. The diameter of the orifices differs for
natural (CE:G20/G25) and LP (CE:G31) gas as indicated in the accompanying table.
NON-CE (Altitudes of 2000 feet or less)
EQUIPMENT
PRESSURE
MODEL
INPUT
(BTU)
GAS
TYPE
ORIFICE
MM
(INCH)
ORIFICE
PART NO.
QTY
MBAR INCH W.C.
FGP55 90
NAT
LP
2.53(#38)
1.51(#53) 810-2048
810-2059 4
4 10
27.5
4
11
CE ONLY (Altitudes of 2000 feet or less)
EQUIPMENT
PRESSURE
MODEL
INPUT
(kW)
GAS
TYPE
ORIFICE
MM
(INCH)
ORIFICE
PART NO.
QTY/
COLOR
MBAR INCH W.C.
FGP55 26.4
G20
G25
G31 2,53
2,53
1,51 810-2048
810-2048
810-2059 4/BLUE
4/BLUE
4/RED
10,0
15,0
27,0 4,0
6,0
10,8
An electromechanical gas valve regulates gas flow to the manifold. FGP55 Series gas rethermalizers
are equipped with a 24-volt valve system. Current units are configured with an electronic standing
pilot system.
Pilot System Configuration
In older units a pilot system comprised of the pilot orifice, pilot hood, and a thermopile were used.
The pilot serves two purposes. The first is to light the burner, the second is to heat the thermocouple
(some systems incorporate a thermopile). In operation, the thermocouple is in contact with the pilot
flame and generates millivolts. The millivolt output energizes the gas valve pilot coil, which in turn
opens the pilot valve. If the pilot flame is extinguished, voltage is lost to the gas valve pilot coil and
the pilot valve closes. The gas valve is constructed so that the main valve will not open if the pilot
valve is not open. The pilot flame must be manually lit when the rethermalizer is first placed into
operation. A separate 120-volt circuit, activated by the rethermalizer power switch, provides voltage
through the electronic thermostat controller to the gas valve main coil, which opens the main valve.
Electronic Ignition Configuration
In units configured for electronic ignition, an ignition module connected to an ignitor assembly
replaces the pilot system. The ignition module performs three important functions: it provides an
ignition spark, supplies voltage to the gas valve, and proofs the pilot flame.