JULY 30, 2014
3
3500 SERIES CONVECTION STEAMERS
PRINCIPLES OF OPERATION
The 3500 Pressureless Steam Cooker consists of two
identical cooking compartments, one above the other,
in a single cabinet assembly. Each compartment is fitted
with independent electrically controlled steam circuits and
spring-loaded, self-sealing doors with slam action latches.
Compartments can be used separately or simultaneously
for either constant steam or 60 minute timing. The prin-
ciples of operation in this section include an explanation
of steam, steam condensing, and electrical circuits and
their functioning.
PLUMBING CIRCUITS
The plumbing circuits consist of the piping, steam sole-
noid valves, orifice, drain, and cold water condenser re-
quired to provide controlled steam application to the cook-
ing compartments. A simplified diagram of these circuits is
shown on the following page.
NOTE: This is strictly a pictorial schematic diagram and
is not intended to show the actual configuration of
the plumbing. All components are shown in cor-
rect relationship with each other. However, the
diagram does not show their actual locations or
position within the cooker.
As shown in the diagram, steam inlet and exhaust con-
nections are connected at the factory directly into a steam
boiler or direct-connected steam plumbing enclosed
within the base cabinet on which the cooker is mounted.
The boiler (or direct-connected steam control system)
is equipped to supply constant, regulated steam at 14–
15 PSI. Steam exhaust, having been reduced to water by
the cold water condenser, is directed into the boiler (or
direct-connected steam control) drain system. Steam inlet
lines for compartments are equipped with normally closed
solenoid valves operated by the electrical control circuits.
The inlet valves are opened whenever the compartment
control circuit is activated by use of the 60 minute timers.
STEAM INLET LINE
A steam supply line is plumbed from the boiler output (or
direct-connected steam control) to a 1/2 inch barb fitting
connected to the input sides of both steam inlet solenoid
valves. When a cooking compartment is not in use, the
valve for the compartment remains closed to prevent
steam from entering. During operation, the appropriate
inlet solenoid valve is opened by activation of the control
circuit.
Steam is projected onto the surface of pans of food load-
ed into the compartment by an orifice located inside the
compartment. Steam continues to flow through the com-
partment in this manner until the control circuit closes the
solenoid valve.
STEAM EXHAUST AND DRAIN LINES
Perforated strainers at the drain line openings inside each
compartment allow only steam, condensation, and liquid
cooking drainage to enter. Prior to discharge into the boil-
er drain system, steam is converted to water by the cold
water condensing systems for each compartment.
STEAM EXHAUST CONDENSING SYSTEM
The steam condensing system consists of the identical,
two-position, normally closed cold water solenoid valves,
with outlet sides connected into the exhaust plumbing for
each cooking compartment. A spray nozzle directs cold
water about the inside of the drain lines to increase cold
water contact with exhausted steam.
Valve inlet sides are connected remote from the supply
line of the steam boiler (or direct-connected steam plumb-
ing). The valves respond to a thermostatic switch located
inside the compartment. When the timer starts the cold
water solenoids will energize.
ELECTRICAL CIRCUITS
The electrical circuits of the cooker control the power to
activate timer motors and energize solenoid-operated
valves and circuits, which in turn control application of
steam to the cooking compartment and condensation
of steam from the exhaust line. The cooker operates on
120V, 2 amp, 60Hz electrical service connected to all cir-
cuits from the circuits of the steam boiler (or direct-con-
nected steam controls) contained within the cabinet on
which the cooker is mounted. Power is supplied to the
control circuit at all times when the shut-off device for the
unit (supplied by the user) is in the ON position.
CONTROL CIRCUIT COMPONENTS
A brief description of the electrical circuit elements fol-
lows.
INDICATOR LIGHTS
An indicator light is included for both compartments. The
light remains on (red) at all times when the coinciding tim-
er dial is set and the door interlock switch is closed. The
light turns off at the end of the timed cooking duration.
BUZZER
The buzzer is an alarm device that operates by oscillation
of a striker against the core of an electromagnet. When
the 60 minute timer dials reach the “0 Minute” position,
the buzzer coil is energized to sound the buzzer. Move-
ment of the timer dial to the OFF position opens the con-
tact to the buzzer coil to shut it off.