VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
boiler shell, remove and clean the Aux LLCO probe.
a.Replace the probe and check resistance again. If resistance is still present, install a new probe.
b.Replace lead wire on probe and repeat steps "2) thru 4)" to verify proper operation.
PRESSURE SWITCHES
4.The cycling pressure switch will maintain the steam pressure setting in the boiler by cycling the main burner ON and OFF.
High Limit
Adjusting the High Limit pressure switch from a cold startup is the preferred condition of the boiler. On the initial cold startup, the highest overshoot pressure (drift) is achieved after the burner cycles OFF for the first time. If the boiler is already operating, the pressure setting can still be made after following the procedures outlined below.
WARNING: THE FOLLOWING STEPS REQUIRE POWER TO BE APPLIED TO THE UNIT DURING THE TEST. USE EXTREME CAUTION AT ALL TIMES.
Remove the cover from the pressure switch control box to access the two pressure switches. The pressure switch near the front is the cycling pressure switch and the one beside it is the high limit pressure switch.
Cycling
1.If the boiler is already operating, proceed to step 2. If the boiler is not already operating, start the boiler as outlined under "CABINET BASE BOILER" in "STEAMER OPERATION".
2.Turn one of the cooking compartment timers ON to exhaust steam from the boiler.
3.Monitor the boiler pressure gauge for several cycles and note the pressures at which the burner comes ON and goes OFF.
A.The main burner should come ON at 8 PSI and go OFF at 10 PSI. If the readings differ, adjust the pressure settings as described below.
1)Two pressure adjustment screws extend through the top of the switch case. The screw directly above the right side pointer raises or lowers both the
The screw directly above the left side pointer raises or lowers the
2)Turn the adjustment screw above the right side pointer to obtain the proper
a.A clockwise rotation increases the pressure setting while a counterclockwise rotation decreases the pressure setting.
1.The high limit pressure switch should be adjusted to allow a maximum pressure in the boiler of 14.5 to 15.0 PSI. Before making adjustments to the high limit pressure setting, the 13 PSI pressure relief valve (PRV- left side) must be temporarily disabled. This will allow a high enough pressure in the boiler to properly set the switch.
A.The suggested methods to prevent the valve from releasing pressure are:
1)Use a wooden block, a hand tool or other object to hold the valve plunger down.
2)Use a metal wire threaded through the hole in the valve handle and tie the pressure relief valve handle to the piping below it.
3)If neither of the two methods keep the valve fully closed without leaks, an alternate method is:
a.Turn the power switch OFF and allow the boiler to blowdown.
b.Remove the discharge piping from the valve outlet and insert a pipe plug for temporary use only.
2.Turn the power switch ON and allow the boiler to completely fill.
A.High Pressure and Low Water indicator lights (amber) come ON.
3.When water in the boiler reaches the minimum level, the green light on the reset switch will come ON.
A.Press the reset switch on the front control panel to reset the High Pressure and Low Water safety controls.
1)Ignition sequence starts, main burner lights and water in the boiler begins to heat.
4.Monitor the boiler pressure gauge and note the pressure at which the high limit switch opens.
NOTE: In front of the boiler there is an additional
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| F24700 (October 2001) |
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