Honeywell VR8200H - Safety Shutoff Operation Details; Pilot Flame Goes Out Procedure

68-0046—4 14
VR8200, VR4200
OPERATION
Fig. 15—Position of gas control components during the thermostat on cycle.
SAFETY SHUTOFF OPERATION
In the safety shutoff position, pilot and main burner gas
flow is permitted.
Safety shutoff occurs:
• When the gas control knob is manually turned to OFF.
• When the pilot goes out or becomes too small to
sus-tain normal ignition.
Gas Control Knob Turned to OFF
When the gas control knob is turned to OFF, it pulls up
and locks the reset button and closes the first automatic
valve. The small valve seat attached to the reset button
closes and shuts off pilot gas flow. When the pilot goes out,
thermocouple current drops and the power unit drops out,
closing the safety shutoff valve. This shuts off pilot and
main burner gas flow. With the loss of outlet pressure, the
second automatic valve closes and is held closed by spring
pressure on the diaphrahm.
When Pilot Flame Goes Out
When pilot flame goes out or is too small to reliably light
the main burner, thermocouple output drops below the
power unit hold-in valve. The power unit drops out, closing
the safety valve and stopping all gas flow through the con-
trol. With the loss of outlet pressure, the second automatic
valve closes and is held closed by spring pressure on the
diaphragm.
FIRST
AUTOMATIC
VALVE
SOLENOID
GAS 
CONTROL KNOB
GAS 
CONTROL
INLET
SAFETY
SHUTOFF VALVE
RESET BUTTON
VALVE DISC
POWER UNIT
SECOND
AUTOMATIC VALVE 
OPERATOR
SECOND 
AUTOMATIC
OPERATOR
SOLENOID
SECOND
AUTOMATIC
OPERATOR
VALVE DISC

SERVO 
PRESSURE
REGULATOR
GAS 
CONTROL 
OUTLET
SECOND AUTOMATIC
VALVE DIAPHRAGM
FIRST
AUTOMATIC
VALVE
M6919
1
1

PILOT
GAS
OUTLET

NOTE: SECOND AUTOMATIC VALVE OPERATOR AND 
SERVO PRESSURE REGULATOR SHOWN OUTSIDE OF
GAS CONTROL FOR EASE IN TRACING GAS FLOW.
SLOW-OPENING GAS CONTROL HAS A GAS 
FLOW RESTRICTOR IN THIS PASSAGE.
RED RESET
BUTTON