Honeywell VS8420C Installation Instructions Manual Download Page 2

VS8420C,M MILLIVOLT GAS VALVE

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WARNING

Fire or Explosion Hazard.
Can cause property damage, severe injury or 
death.
Follow these instructions exactly:

1. Turn off gas supply at the appliance service 

valve before starting installation, and perform 
a Gas Leak Test after the installation is com-
plete.

2. Always install the sediment trap in the gas 

supply line to prevent contamination of the 
gas valve.

3. Do not force the gas valve control knob. Use 

only your hand to turn the control knob. If the 
knob does not operate by hand, the valve 
should be replaced by a qualified service 
technician.

WARNING

Electrical Shock or Equipment Damage Haz-
ard.
Can cause equipment damage, serious 
injury or death.
Disconnect all power supplies before installa-
tion.

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 avail-
able; otherwise, use these instructions.

Converting 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. When making a conver-
sion, change the main pilot burner orifices to 
meet the appliance manufacturer specifications.

VS8420M gas controls with Convertible High/Low regu-
lators can be converted from one gas to the other with a 
conversion kit (ordered separately). Order part number 
396087-1 to convert from LP to natural gas. order part 
number 396087-2 to convert from natural gas to LP.

High/low regulator model VS8420C cannot be 
converted.

Location

Locate the combination gas valve where it cannot be 
affected by steam cleaning, high humidity, dripping 
water, corrosive chemicals, dust or grease accumula-
tion 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

Tubing installation must comply with approved stan-
dards 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 tub-
ing to the valve.

3.

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

Install Valve (Using Pipe)

1.

Mount valve 0 to 90 degrees, in any directionÑin-
cluding verticallyÑfrom 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 15 mm. Do not insert deeper than10 
mm. 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 nece-
sary.

6.

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

Summary of Contents for VS8420C

Page 1: ...ith EN 88 class C Natural Gas 9 mbar typical LP 27 mbar typical Regulator Adjustments Standard Regulator Natural Gas 7 5 mbar to 12 5 mbar field adjustable LP 20 mbar to 30 mbar field adjustable In appliances where no regulation is required the pres sure regulator must be blocked by turning the pressure regulator adjustment screw fully down The regulator will then be set at 30 mbar Voltage VS8420 ...

Page 2: ...onvert from natural gas to LP High low regulator model VS8420C cannot be converted Location Locate the combination gas valve where it cannot be affected by steam cleaning high humidity dripping water corrosive chemicals dust or grease accumula tion 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 ex...

Page 3: ...pilot burner according to the manufacturer s instructions WARNING Fire or Explosion Hazard Can cause property damage severe injury or death Do not bend tubing at gas valve after compres sion fitting has been tightened as this may result in a gas leak at the connection Fig 3 Top view of gas valve with HI LO regulator Fig 4 Top view of gas valve with standard regulator GAS CONTROL GAS CONTROL HORIZO...

Page 4: ...ting stamped on the valve operator Table 1 Maximum Thermostat Wire Length ECO Connection Supplementary 1 Push the ECO into the window of the gas valve See Fig 5 2 The leadwires of the ECO must be equipped with insulated 6 3 mm female quick connect terminals 3 Leadwire length must not exceed the length as shown in Table 2 Table 2 Maximum Length mm of Supplementary Limit Leadwires When Using Q309A T...

Page 5: ...erclockwise to the ON position On a call for heat the main valve opens and the main burner ignites Shut off Procedure 1 To shut off the system turn the knob clockwise to the OFF position This action closes the main gas and safety valves however the power unit must drop out before the lighting sequence can begin again The VS8420 drops out within 30 seconds 2 To relight the pilot light follow the st...

Page 6: ...ot 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 ...

Page 7: ...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 lit...

Page 8: ...ff 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 techni cian 5 The gas val...

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