Vulcan-Hart VHX24E service manual Water Refill After Initial Fill, Boiler Blowdown/drain

VHX SERIES STEAMER - ELECTRICAL OPERATION

1)K4(1) N.O. contacts close and K4(1) N.C. contacts open.

2)High pressure light goes out.

3)K4(2) N.O. contacts close.

a.AUX contactors A & C energized, heating elements powered.

NOTE: As boiler heats up and builds pressure, some by-pass water/steam is produced which runs into the steam drain box. This causes the cold water condenser (CWC) solenoid to cycle, cooling the drain water and condensing any steam vapors before exiting the drain. The CWC solenoid is powered through the CWC cycling thermostat.

7.Boiler steam pressure reaches upper limit set point of 12 PSI (Approx. 15 minutes).

A.Cycling pressure switch opens.

1)Cycling contactors B & D de- energized and power is removed from heating elements.

8.Boiler steam pressure drops below lower limit set point of 10 PSI and the cycling pressure switch closes.

A.Cycling pressure switch continues to cycle between the upper and lower set point limits. This energizes and de-energizes the heating elements to maintain pressure in the boiler.

This sequence continues until one of the following occurs:

1)Power switch is turned off.

2)Boiler water level drops below the LLCO probe for the main water level control and the AUX LLCO probe for the auxiliary water level control.

3)Boiler pressurizes to 15 PSI, causing the high limit pressure switch to open.

Water Refill (After Initial Fill)

1.Water level drops below low level probe (LL).

A.HL relay is energized.

1)HL-3 (N.O.) contacts close.

2)Boiler fill valve is energized.

3)HL LED comes on.

2.Water reaches LL (low level) probe.

3.Water reaches high level probe.

A.HL relay is de-energized.

1)HL-3 (N.O.) contacts open.

2)Boiler fill valve is de-energized.

3)HL LED goes out.

4.The water refill cycle will occur whenever the water level is below the low level probe and will not affect the operation of either the preheat or cook cycle.

Boiler Blowdown/drain

1.Power switch turned off.

A.Automatic blowdown valve (N.O.) is de- energized and valve opens to drain the boiler.

B.Power is removed from all components except cold water condenser (CWC) thermostat and solenoid valve. The CWC thermostat cycles as necessary to lower the discharge temperature of the water and condense steam going into the drain.

COOKING COMPARTMENT CONTROLS

1.Conditions.

A.Doors shut (closes the N.O. door switch contacts).

B.Cooking timers off.

C.Compartment pressure switch contacts open.

2.With boiler at operating pressure.

A.Cooking compartment pressure switch closes (approx. 3 PSI).

1)Cooking compartment ready light (green) comes on.

3.Start a cook cycle.

A.Insert product into steamer and close door.

B.Set a cook time.

NOTE: On initial startup, if a cooking timer is set immediately after the ready light comes on, steam solenoid chattering will be heard (oil canning) and the ready lights will flash for several seconds. This condition is caused by the manifold steam pressure being on the fringe of the pressure switch set point. When a cook timer is set, the compartment steam solenoid valve opens causing the manifold steam pressure to drop, slightly below the pressure switch set point. At the same time, steam pressure is still increasing in the boiler. This opposing condition causes a pressure bounce to occur. After the steam pressure passes approximately 4 psi this condition subsides. During normal operation, this condition will not be seen.

C.Contacts 1/3 of cook timer close and timer motor is energized.

F25154 (February 2004) Page 34 of 48