VS8421 VENTFREE MILLIVOLT GAS VALVE
7
69-1219—1
MAINTENANCE
WARNING
Fire or Explosion Hazard.
Can cause property damage, severe injury or
death.
Do not attempt to take apart the gas valve or
clean it. Improper assembly and cleaning can
cause unreliable operation.
Regular preventive maintenance is important in
applications that place a heavy load on system controls
such as those used in the commercial cooking and
agricultural and industrial industries because:
•
In applications such as commercial cooking, the
equipment operates 100,000 to 200,000 cycles per
year. This heavy cycling can wear out the gas valve in
one to two years.
•
Exposure to water, dirt, chemicals and heat can
damage the gas valve and shut down the control
system.
The maintenance program should include regular system
checkout as outlined in the Checkout section, and
checkout of the control system as described in the
appliance manufacturer literature.
Maintenance frequency must be determined individually
for each application:
•
Cycling frequency—Appliances that cycle 20,000
times annually should be checked monthly.
•
Intermittent use—Appliances that are used seasonally
should be checked before shutdown and again before
the next use.
•
Consequence of unexpected shutdown—Where the
cost of an unexpected shutdown would be high, the
system should be checked more often.
•
Dusty, wet, or corrosive environment—Because these
environments can cause the gas valve to deteriorate
more rapidly, the system should be checked more
often.
Any valve should be replaced if it does not perform
properly on checkout or service. In addition, replace any
module if it is wet or looks like it has ever been wet.
SERVICE
WARNING
Fire or Explosion Hazard.
Attempted disassembly or repair can cause
property damage, severe injury or death.
Do not disassemble the gas valve; it contains no
replaceable components.
CAUTION
Equipment Damage.
Can burn out heat anticipator in thermostat.
Do not apply a jumper across (or short) the valve
coil terminals even temporarily.
If Main Burner Does Not Come On With
Call For Heat
1.
Confirm that the gas control knob is in the ON
position.
2.
Adjust the thermostat several degrees above the
room temperature.
3.
Use a dc voltmeter to measure the voltage across
the THTP and TP terminals.
4.
If no voltage is present, check the control circuit for
proper operation.
5.
If proper control system voltage is present, replace
the gas valve.
Warning To The Appliance Owner.
For Your Safety, Read Before Lighting
Appliance.
WARNING
Fire or Explosion Hazard.
Can cause property damage, severe injury
or death.
Exactly follow the instructions for Pre-Lighting
Checks.
Pre-Lighting Checks
1.
Before lighting, smell around the appliance area for
gas. If the appliance uses LP gas, be sure to smell
next to the floor because LP gas is heavier than air.
2.
If you smell gas, immediately shut off the manual
valve in the gas piping to the appliance or, on LP, at
the tank. Leave the building immediately and call
your gas supplier. If your gas supplier cannot be
reached, call the fire department.
3.
Do not force the gas valve control knob. Use only
your hand to turn the control knob.
4.
If the knob does not operate by hand, the valve
should be replaced by a qualified service
technician.
5.
The gas valve must be replaced if it was flooded
with water. Call a qualified service technician.
6.
The gas valve is a safety device. It must be
replaced in the event of any physical damage such
as bent terminals, missing or broken parts, stripped
threads, or evidence of exposure to heat.
IMPORTANT
Follow the operating instructions provided by
the manufacturer of your heating appliance.
Troubleshooting Guide
Fire or Explosion Hazard.
Can cause property damage, severe injury or death.
Only a qualified service technician should perform these
troubleshooting procedures.
Use Fig. 7 and Table 2 as a troubleshooting guide for the
VS8421.
69-1219-1.fm Page 7 Thursday, August 18, 2011 7:32 AM