Electrical Operation; Component Function; Cabinet Base Boiler Controls - Vulcan-Hart MHB24E Service Manual

COMPONENT FUNCTION

Power Switch . . . . . . . . . . . . . . . . Controls 120VAC to the boiler control circuit.
Reset Switch (Manual) . . . . . . . . . Resets the low water level safety circuit on initial startup or the occurrence of
Boiler Fill Valve . . . . . . . . . . . . . . . Allows water flow to the boiler when energized thru HL-3 contacts on the
Cold Water Condenser
Valve . . . . . . . . . . . . . . . . . . . . . . . Allows cold water to spray thru a nozzle inside the condenser drain box to
Cold Water Condenser
Cycling Thermostat . . . . . . . . . . . Regulates cold water spray inside the condenser drain box during a cooking
Cycling Pressure Switch . . . . . . . Regulates boiler pressure between cut-out (off) and cut-in (on) pressure
High Limit Pressure Switch . . . . . Prevents boiler from reaching pressures above 15 PSI by removing power
Main Water Level Control . . . . . . A dual function control that allows water to fill and maintain the proper level
Auxiliary Water Level Control . . . A back up to the low level cut-off on the main water level control. Protects
Relay Board . . . . . . . . . . . . . . . . . . Provides a centralized location for wire harness connections and power
NOTE: The relay's below are mounted on the relay board and are individually replaceable.
K1 Relay . . . . . . . . . . . . . . . . . . . . Energized when water level reaches the Aux LLCO probe (water level
K2 Relay . . . . . . . . . . . . . . . . . . . . Energized when high limit pressure switch is closed (high limit pressure
K3 Relay . . . . . . . . . . . . . . . . . . . . Energized when K1(2) N.O. contacts close and reset switch is activated.
K4 Relay . . . . . . . . . . . . . . . . . . . . Energized when K2(2) N.O. contacts are closed and reset switch is
F25154 (February 2004)
VHX SERIES STEAMER - ELECTRICAL OPERATION

ELECTRICAL OPERATION

CABINET BASE BOILER CONTROLS

a low water condition. Also, resets the high pressure level safety circuit on
initial startup or the occurrence of a high pressure condition which allows
heating to start.
water level control.
condense steam and cool the hot water before discharging into the drain.
cycle or boiler blowdown/drain.
settings of switch.
from heating circuit. The high limit automatically resets at approximately 12
psi (green ready light on).
in the boiler, providing differential level control; and removes power from
heating circuit if water level drops too low, providing low level cut-off
protection. The control uses three different probe lengths to monitor water
level (high level HL, low level LL, low level cut-off LLCO).
boiler and heating system components from a low water cut-off condition by
opening the 120VAC voltage path to the heating circuit. The control uses a
single probe to monitor water level (auxiliary low level cut-off Aux LLCO).
transfer thru board relays (K1-K4) to the steamer controls. Also, provides
voltage test points (T1-T7) for verifying voltage to relay coils, N.O. relay
contacts closed, control panel lights and auxiliary contactor coils.
condition satisfied).
condition satisfied). When K1 & K2 are energized, ready light (green) will be
on.
When K3 is energized, K3(2) N.O. contacts close and low water light turns
off.
activated. When K4 is energized, K4(2) N.O. contacts close and high
pressure light turns off. When K3 and K4 are energized, power is supplied to
auxiliary contactors A & C.
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