VS8420C,M MILLIVOLT GAS VALVE
69-1304
6
Standard Pressure Regulator
1.
Check the manifold pressure listed on the appli-
ance nameplate. Gas valve outlet pressure
should match the nameplate.
2.
With the main burner operating, check the gas
valve flow rate using the meter clocking method
or measure the pressure by attaching a plastic
tube with a 9 mm OD (1/4 in. shell ID) to the pres-
sure gauge and connecting the pressure gauge to
the outlet pressure tap on the gas valve. See Fig.
4. When checking the pressure, undo the screw a
half turn and slip tube over nipple. Make sure that
screw is re-tightened after completing test.
3.
If necessary, adjust the pressure regulator to
match the appliance rating. See Table 1 for fac-
tory-set nominal outlet pressure and adjustment
range.
a. Remove the pressure regulator adjustment
cap screw.
b. Using a screwdriver, turn the inner adjustment
screw clockwise
to increase or coun-
terclockwise
to decrease gas pressure
to the burner.
c. Always replace the cap screw and tighten
firmly to prevent gas leakage.
4.
If desired outlet pressure or flow rate cannot be
achieved by adjusting the gas valve, check the
gas valve inlet pressure using a manometer at the
gas valve inlet pressure tap. If inlet pressure is in
the normal range (see Table 3), replace the gas
valve; otherwise, take the necessary steps to pro-
vide proper gas pressure on the valve.
CHECKOUT
WARNING
Fire or Explosion Hazard.
Can cause property damage, severe injury or
death.
Do not force the gas control knob on the appli-
ance. Use only your hand to turn the gas control
knob. If the knob does not operate by hand, the
valve should be replaced by a qualified service
technician.
Gas Control Knob Settings
Gas control knob settings are as follows:
•
OFF: Prevents main gas flow through the valve.
•
ON: Permits main burner and pilot gas flow. Gas
valve and thermostat control main burner gas flow.
•
PILOT: Opens pilot valve and allows gas flow to the
pilot burner.
•
HI/LO: Manually adjusts outlet pressure.
NOTE:
Valves are shipped with the gas control knob in
the ON position.
Perform Gas Leak Test
WARNING
Fire or Explosion Hazard.
Can cause property damage,severe injury or
death.
Stand away from the main burner while lighting.
Hidden gas leaks can cause flashbacks in the
appliance vestibule. Check for gas leaks with
rich soap and water solution any time work is
done on a gas system.
Gas Leak Test
1.
Paint the pipe connections upstream of the gas
valve with a rich soap and water solution. Bubbles
indicate a gas leak.
2.
If a leak is detected, tighten the pipe connections.
3.
Light the main burner.
4.
With the main burner in operation, paint the pipe
joints (including adapters) and valve inlet and out-
let with a rich soap and water solution.
5.
If another leak is detected, tighten the adapter
screws, joints, and pipe connections.
6.
Replace the part if the leak cannot be stopped.
Turn on System
Rotate the gas control knob counterclockwise
to
ON.
Turn on Main Burner
Follow the instructions provided by the appliance manu-
facturer or turn up the thermostat to call for heat.
Check and Adjust Gas Input and Burner
Ignition
IMPORTANT
Do not exceed the input rating stamped on the
appliance nameplate, or the manufacturer rec-
ommended burner orifice pressure for size ori-
fice(s) used.
IMPORTANT
For complete combustion, be sure the primary
air supply to the main burner is adjusted prop-
erly. Follow the instructions of the appliance
manufacturer.
Checking Gas Input By Clocking Gas Meter
1.
Be sure there is no gas flow through the meter
except to the appliance being checked.
NOTE:
Other appliances must remain off with the
pilots extinguished, or the consumption must
be deducted from the meter reading.
2.
Convert the flow rate to Btuh as described in the
Gas Controls Handbook, form 70-2602.
3.
Compare to the Btuh input rating on the appliance
nameplate.