Honeywell VS8521 Installation Instructions Manual Download Page 2

VS8521 VENTFREE MILLIVOLT GAS VALVE

69-1223—1

2

CAUTION

Equipment Damage.
Can burn out heat anticipator in thermostat.
Never apply a jumper across or short the valve 
coil terminals.

IMPORTANT

These gas valves are shipped with protective 
seals over the inlet and outlet tappings. Do not 
remove the seals until ready to connect the 
piping.

Follow the appliance manufacturer instructions, if 
available; otherwise, use these instructions.

IMPORTANT

The VS8521 ventfree valve is not convertible 
between natural and LP gas.

WARNING

Fire or Explosion Hazard.
Can cause property damage, severe injury or 
death.
Do not use a gas valve set for natural gas on an 
LP gas system or a gas valve set for LP gas on a 
natural gas system. Gas valves are factory-set for 
natural (and manufactured) or LP gas. 

VS8521 ventfree valves are not convertible.

Location

Locate the combination gas valve where it cannot be 
affected by steam cleaning, high humidity, dripping water, 
corrosive chemicals, dust or grease accumulation or 
excessive heat. To assure proper operation, follow these 
guidelines:

Locate gas valve in a well-ventilated area.

Mount gas valve high enough to avoid exposure to 
flooding or splashing water.

Assure the ambient temperature does not exceed the 
ambient temperature ratings for each component.

Cover gas valve if appliance is cleaned with water, 
steam, or chemicals or to avoid dust and grease 
accumulation.

Avoid locating gas valve where it can be exposed to 
corrosive chemical fumes or dripping water.

Install Piping to Gas Valve

All piping must comply with local codes and ordinances 
or with the National Fuel Gas code (ANSI Z223.1 
NFPA No. 54), whichever applies. Tubing installation 
must comply with approved standards and practices.

1.

Use new, properly reamed pipe free from chips. 
When tubing is used, assure the ends are square, 
deburred and clean. All tubing bends must be 
smooth and without deformation.

2.

Run pipe or tubing to the valve. If tubing is used, 
obtain a tube-to-pipe coupling to connect the 
tubing to the valve.

3.

Install sediment trap in the supply line to the gas 
valve. See Fig. 1.

Install Valve

1.

Mount valve 0 to 90 degrees, in any direction—
including vertically—from the upright position of the 
gas control knob.

2.

Mount the valve so gas flow is in the direction of 
the arrow on the side of the valve.

3.

Thread pipe 9/16 in. into the valve. Do not insert 
deeper than 3/8 in. Valve distortion or malfunction 
can result if the pipe is inserted too deeply.

4.

Apply a moderate amount of good quality pipe 
compound (do not use Teflon tape) to pipe only, 
leaving two end threads bare. On LP installations, 
use compound resistant to LP gas. See Fig. 2.

5.

Remove seals over valve inlet and outlet, if 
necessary.

6.

Connect pipe to valve inlet and outlet. Use wrench 
on either side of the pipe outlet. Refer to Fig. 3 
through 5.

Fig. 1. Sediment trap installation.

Fig. 2. Use moderate amount of pipe compound.

GAS
CONTROL

GAS
CONTROL

HORIZONTAL

DROP

PIPED
GAS
SUPPLY

PIPED
GAS
SUPPLY

3 INCHES
(76 MM)
MINIMUM

3 INCHES
(76 MM)
MINIMUM

RISER

GAS
CONTROL

TUBING
GAS
SUPPLY

HORIZONTAL

DROP

3 INCHES
(76 MM)
MINIMUM

RISER

M4603A

1

1

CAUTION

GAS LEAKAGE HAZARD. 
FAILURE TO FOLLOW PRECAUTIONS CAN 
RESULT  IN A GAS-FILLED WORK AREA.
SHUT OFF THE MAIN GAS SUPPLY BEFORE REMOVING END CAP.  
TEST FOR GAS LEAKAGE WHEN INSTALLATION IS COMPLETE.

ALL BENDS IN METALLIC TUBING SHOULD BE SMOOTH.

TWO IMPERFECT 
THREADS

GAS CONTROL

THREAD PIPE ACCORDING TO
INSTALLATION PROCEDURE FOR 
INSERTION INTO GAS CONTROL. 

APPLY A MODERATE AMOUNT OF
PIPE COMPOUND TO PIPE ONLY
(LEAVE TWO END THREADS BARE).

M6913

PIPE

Summary of Contents for VS8521

Page 1: ...2 European Community CE Certificate Applied for INSTALLATION When Installing this Product 1 Read these instructions carefully Failure to follow them could damage the product or cause a hazardous condition 2 Check the ratings given in the instructions and on the product to make sure the product is suitable for your application 3 Installer must be a trained experienced service technician 4 After ins...

Page 2: ... comply with approved standards and practices 1 Use new properly reamed pipe free from chips When tubing is used assure the ends are square deburred and clean All tubing bends must be smooth and without deformation 2 Run pipe or tubing to the valve If tubing is used obtain a tube to pipe coupling to connect the tubing to the valve 3 Install sediment trap in the supply line to the gas valve See Fig...

Page 3: ...nect power supply before making wiring connections to prevent electrical shock or equipment damage 1 Check the power supply rating on the gas valve and make sure it matches the available supply Install the transformer thermostat and other controls as required 2 This valve can be used only in a self generating system 3 Adjust the thermostat heat anticipator to the 0 1A at 750 mV rating stamped on t...

Page 4: ...lve counterclockwise to the PILOT position push the knob down and hold in position The pilot valve opens and allows gas to flow to the pilot burner 2 Push the plunger on the piezo until the pilot burner is lit Hold down the knob until a strong flame is present approximately 60 seconds 3 Release the knob The shaft will move upward and engage the safety valve lever that opens the safety valve 4 Turn...

Page 5: ...ner 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 d...

Page 6: ...perly 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 ind...

Page 7: ...zard 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 ...

Page 8: ...C Thermocouple Have thermostat contacts open and pilot lit with Pilotstat knob turned to PILOT Reading should be a minimum of 12 mV in a new ODS pilot burner assembly If the reading is less than 12 mV replace the ODS pilot burner assembly The power unit will hold in down to 3 mV If the output of the thermocouple is less than 3 mV replace the ODS pilot burner assembly 4 Test D Operator Pull In have...

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