Honeywell VS8510, VS8520 Millivolt Gas Valve

APPLICATION

The VS8510, VS8520 Millivolt Gas Valve is compact and has a 60,000 Btuh capacity (1 in. pressure drop for straight through configuration). Its design makes it ideal for fireplace and space heating applications.

SPECIFICATIONS

• Main Gas Connection: Valve: 3/8 in. NPT thread.
• Pilot Gas Connection and Flow: Connection Size: 7/16-24 UNS. Flow: 1700 Btuh at 4.0 in. wc pressure drop.
• Thermocouple and Pilot Threads: Metric and UNS.
• Ambient Temperature Range: 0°F to 175°F (-18°C to 79°C). Option for 225°F (107°C).
• Pressure Regulation: Servo regulator with adjustable outlet pressure. Natural Gas: Typically 3.5 in. wc. LP: Typically 11 in. wc.
• Regulator Adjustments: Natural Gas: 3.0 to 5.0 in. field adjustable. LP: 8.0 to 12.0 in. field adjustable.
• Models: VS8510: 750 mV operator, 30 mV thermocouple. VS8520: 750 mV operator, 30 mV thermocouple.
• Certifications: International Approval Services (IAS) Certificate; 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 appliance nameplate to make sure the product is suitable for your application.
3. Installer must be a qualified, experienced service technician.
4. After installation is complete, check product operation as provided in these instructions.

▲ WARNING

Oxygen depletion hazard. Can cause injury or death due to asphyxiation.

• Use only vented gas valve models on vented appliances.
• Use only unvented gas valve models on unvented appliances.

▲ WARNING

Fire or explosion hazard. Can cause property damage, severe injury or death.

Follow these warnings exactly:

1. Disconnect power supply before wiring to prevent electrical shock or equipment damage.
2. To avoid dangerous accumulation of fuel gas, turn off gas supply at the appliance service valve before starting installation, and perform a Gas Leak Test after the installation is complete.
3. Always install the sediment trap in the gas supply line to prevent contamination of the gas control.
4. Do not force the gas control knob. Use only your hand to turn the gas control knob. Never use any tools. If the gas control knob does not operate by hand, the gas control should be replaced by a qualified service technician. Force or attempted repair can result in fire or explosion.

Converting Between Natural and LP Gas

▲ WARNING

Fire or explosion hazard. Can cause property damage, severe injury or death.

1. Do not use a gas control set for natural gas on an LP gas system or a gas control set for LP gas on a natural gas system.
2. When making a conversion, the main pilot burner orifices must be changed to meet the appliance manufacturer specifications.

When making a conversion, change main pilot burner orifices to meet the appliance manufacturer specifications. Refer to the appliance manufacturer instructions for orifice specifications and changeover procedure. Gas controls are factory-set for natural (and manufactured) or LP gas. Do not attempt to use a control set for natural (manufactured) gas on LP gas or a control set for LP on natural (manufactured) gas.

VS8510A and VS8520A controls with a standard regulator can be converted from one gas type to another with a conversion kit (ordered separately). Order part no. 395991 to convert from natural gas to LP gas. Order part no. 395992 to convert from LP gas to natural (manufactured) gas.

VS8510 and VS8520 High/Low regulator controls can be converted from one gas to the other with a conversion kit (ordered separately). Order part no. 396087 to convert from natural gas to LP gas. Order part no. 396087-2 to convert from LP gas to natural gas.

VS8510R and VS8520R Convertible Pressure Regulators: Valves with suffix letter R are convertible pressure regulator models. They can be converted from natural gas to LP or from LP to natural gas without a converter kit.

Before converting the gas valve from one gas to another, check the gas valve label and the appliance manufacturer rating plate to make sure the pressure regulator setting (factory set) meets the appliance manifold requirements after conversion.

NOTE:

Convertible pressure regulator models (suffix R) do not have field-adjustable regulators. The natural gas and LP settings are factory-manufactured.

CONVERTING THE GAS VALVE

If the factory pressure regulator setting meets appliance manifold requirement, convert the gas valve as follows (see Fig. 1):

1. Remove the black thread protective cap. Remove the conversion flip cap by turning counterclockwise.
2. Invert the conversion flip cap so the bottom letters and associated numbers for the gas type appear face up toward the valve. NAT is for natural gas and LP is for liquefied petroleum gas.
3. Tighten the flip cap by turning clockwise approximately 1/4 turn. Replace the black thread protective cap.

Fig. 1. Converting the gas valve (shown assembled for natural gas).

Location

Locate the combination gas control 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 control in a well-ventilated area.
• Mount gas control 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 control if appliance is cleaned with water, steam, or chemicals or to avoid dust and grease accumulation.
• Avoid locating gas control where exposure to corrosive chemical fumes or dripping water is likely.

Install Piping to Gas Control

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 control. If tubing is used, obtain a tube-to-pipe coupling to connect the tubing to the control.
3. Install sediment trap in the supply line to the gas control. See Fig. 1.

Install Control

1. Mount control 0 to 90 degrees, in any direction, from the upright position of the gas control knob, including vertically.
2. Mount the control so gas flow is in the direction of the arrow on the side of the control.
3. Thread pipe 9/16 in. into the control. 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 control inlet and outlet, if necessary.
6. Connect pipe to control inlet and outlet. Use a wrench on either side of the pipe outlet fitting to prevent pipe distortion. See Fig. 3 through 5.

Fig. 2. Sediment trap installation.

Fig. 3. Use moderate amount of pipe compound.

Wiring

Follow the wiring instructions furnished by appliance manufacturer, if available, or use the instructions provided below. Where the appliance manufacturer instructions differ from the wiring diagrams, follow the appliance manufacturer instructions. For typical wiring diagrams, see Fig. 6 and 7.

All wiring must comply only with applicable electrical codes and ordinances.

• If power supply is making wiring connections, disconnect power supply before making wiring connections to prevent electrical shock or equipment damage.
• Check to ensure power supply rating on the gas control matches the available supply.
• This valve can only be used in a self-generating circuit.
• Adjust the thermostat heat anticipator to the 0.1A at 7 mV rating stamped on the valve operator.

OPERATION

The Millivolt Gas Valve System has two different configurations. The first configuration includes a gas valve, quick drop-out thermocouple, thermopile, millivolt thermostat and a pilot burner. In this configuration, the thermopile drives the operator and the quick dropout thermocouple operates the power unit. See Fig. 7. The second configuration includes a gas valve, the millivolt thermostat, and a pilot burner. The thermopile drives the operator and the power unit.

Pilot Gas and Lighting Procedure

1. Turn the gas control knob counterclockwise to the PILOT position and hold in position.
2. Light the pilot burner while holding the knob down with a strong flame is present (approximately 60 seconds).
3. Release the knob. The shaft will move upward and the safety valve lever that opens the safety valve will close.
4. Turn the knob counterclockwise 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 VS8510 drops out within three minutes. The VS8520 drops out within 30 seconds.
2. To relight the pilot light, follow the steps in the Pilot Gas and Lighting Procedure section.

HI/LO Regulator

As you turn the HI/LO knob, the gas pressure changes.

1. Turn the knob clockwise towards the HI setting to increase gas pressure.
2. Turn the knob counterclockwise towards the LO setting to decrease gas pressure.

Minimum and maximum regulator settings vary for each individual gas valve. See gas valve label for actual minimum and maximum ranges. Table 1 lists possible minimums and maximums for gas valves.

Fig. 4. Top view of gas control with HI/LO regulator.

Fig. 5. Top view of gas control with standard regulator.

Table 1. HI/LO and Standard Regulator Specification Pressures in in. wc (kPa).

Standard Pressure Regulator

1. Check the manifold pressure listed on the appliance nameplate. Gas control outlet pressure should match the nameplate.
2. With the main burner operating, check the control flow rate using a clocking meter or manometer. Connect a manometer to the gas control outlet pressure tap. See Fig. 5.
3. If necessary, adjust the pressure regulator to match the appliance nameplate. See Table 1 for factory-set nominal outlet pressure and adjustment screw settings.
   • Turn the pressure regulator adjustment cap screw clockwise to increase pressure.
   • Using a screwdriver, turn inner adjustment screw clockwise to increase or counterclockwise to decrease gas pressure.
   • Always replace cap screw and tighten firmly to prevent gas leakage.
4. If desired outlet pressure or flow rate cannot be obtained by adjusting the gas control, check gas control inlet pressure using a manometer at the gas control inlet pressure tap. If inlet pressure is in the normal range (see Table 1), replace gas control. Otherwise, take the necessary steps to provide proper gas pressure on the control.

CHECKOUT

▲ WARNING

Fire or explosion hazard. Can cause property damage, severe injury or death.

1. Do not force the gas control knob on the appliance. Use only your hand to turn the gas control knob. Never use any tools.
2. If the knob does not operate by hand, the control 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 control.
• ON: Permits main burner and pilot gas flow. Gas control and thermostat control main burner gas flow.
• PILOT: Opens pilot valve and allows gas flow to pilot burner.
• HI/LO: Manually adjusts outlet pressure.

NOTE: Controls 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.

1. Stand away from the main burner while lighting. Hidden gas leaks can cause flashbacks in the appliance vestibule.
2. 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 control with rich soap and water solution. Bubbles indicate a gas leak.
2. If a leak is detected, tighten the pipe connections. Light the main burner.
3. With the main burner in operation, paint the pipe joints (including adapters) and control inlet and outlet with a rich soap and water solution.
4. If another leak is detected, tighten the adapter screws, joints, and pipe connections.
5. Replace part if leak cannot be stopped.

Turn on System

Rotate the gas control knob counterclockwise to the ON position.

Turn on Main Burner

Follow the instructions provided by the appliance manufacturer or turn up the thermostat several degrees to call for heat.

Check and Adjust Gas Input and Burner Ignition

CAUTION: Equipment damage. Improper adjustment of gas input and burner ignition can cause malfunctioning or unnecessary shutdown. The appliance manufacturer's nameplate specifies the gas input rating and the required orifice pressure for size of the main burner. Check the primary air supply to the main burner to ensure it is properly adjusted for combustion. Follow the instructions provided by the appliance manufacturer.

CHECKING GAS INPUT BY CLOCKING METER: Be sure there is no gas flow through the meter other than to the appliance being checked. Other appliances must remain off with the pilots extinguished (or the consumption must be deducted from the meter reading). Convert the flow rate to Btuh as described in the Gas Controls Handbook, form 70-2602, and compare to the Btuh input rating on the appliance nameplate.

CHECKING GAS INPUT WITH MANOMETER: Both the inlet and outlet pressure taps have a captive screw. To measure the pressure of the tap, loosen, but do not remove the captive screw, attach a plastic tube with a 1/4 in. shell I.D. and connect the manometer. After checking the pressure, turn the gas control knob to the OFF position. Replace the captive screw. Open the outlet pressure tap. Open the inlet pressure tap by turning the manual shutoff valve in the gas supply to the appliance or, for LP gas, the LP gas tank. Perform Gas Leak Test at the outlet pressure tap before the main burner operates.

Check Safety Shutdown Performance

▲ WARNING

Fire or explosion hazard. Can cause property damage, severe injury or death.

Perform safety shutdown test any time work is done on the gas system.

1. Place gas control knob in PILOT position. Main burner should go off and pilot should remain lit. Extinguish pilot flame. The VS8510 pilot gas flow shuts off within three minutes; the VS8520 pilot gas flow shuts off within thirty seconds. Safety shutoff proves complete shutdown because the safety shutoff valve prohibits main burner and pilot gas flow.
2. Relight pilot burner and operate the system through one complete cycle to ensure all controls operate properly.

MAINTENANCE

▲ WARNING

Fire or explosion hazard. Can cause property damage, severe injury or death.

Do not attempt to take apart the gas control or to 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 many such applications, particularly commercial cooking, the equipment operates 100,000 to 200,000 cycles per year. Such heavy cycling can wear out the gas control in one to two years.
• Exposure to water, dirt, chemicals and heat can damage the gas control and shut down the control system.

The maintenance program should include regular checkout of the system as outlined in the Checkout section, and checkout of the control system as described in the appliance manufacturer literature.

SERVICE

▲ WARNING

Fire or explosion hazard. Can cause property damage, severe injury or death.

Do not disassemble the gas control; it contains no replaceable components. Attempted disassembly or repair can damage the control.

▲ 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 is in the ON position.
2. Adjust the thermostat several degrees to call for heat.
3. Use a voltmeter to measure the voltage across the HTR+ and TH terminals.
4. If voltage is present, check the control circuit for proper operation.
5. If proper control system voltage is present, replace the gas control.

TROUBLESHOOTING

IMPORTANT: Troubleshooting procedures should only be performed by an experienced, qualified service technician.

Use Fig. 9 and Table 2 or 3 to assist in troubleshooting the VS8510 or VS8520.

Fig. 9. Test points for troubleshooting the VS8510/VS8520 Millivolt Gas Valves.

Table 2. VS8510 Troubleshooting Tests.

A-Have thermostat contacts open and pilotstat knob turned to OFF. Coil resistance should be maximum of 3.6 ohms. If not, replace the valve.

B-Have thermostat contacts open and pilot burning with pilotstat knob turned to PILOT. There should be a minimum of 460 mV. If not, replace thermopile.

C-Have thermostat contacts open and pilot burning with pilotstat knob in the PILOT position. Close the thermostat contacts. The thermopile should provide 155 mV. If not, replace the thermopile. If output is 55 mV or greater, the valve operator will make an audible sound or click when it pulls in. If the valve does not make a sound, replace the valve.

D-The system resistance from the remote switch or thermostat and leadwires should not exceed 1.7 ohms. If it does, reduce the resistance.

Table 3. VS8520 Troubleshooting Tests.

A-Have thermostat contacts open and pilotstat knob turned to OFF. Coil resistance should be maximum of 3.6 ohms. If not, replace the valve.

B-Have thermostat contacts open and pilot burning with pilotstat knob turned to PILOT. There should be a minimum of 460 mV. If not, replace thermopile.

C-Have thermostat contacts open and pilot burning with the pilotstat knob turned to PILOT. The voltage should be 18 mV for a new thermocouple. You must push in the pilotstat knob to maintain the gas flow. If the output does not meet the minimum voltage, replace the thermocouple. The power unit should hold in down to 3 mV. If the output of the thermocouple is below 3 mV, replace the thermocouple.

D-Have thermostat contacts open and pilotstat knob in the PILOT position. Close the thermostat contacts. The thermopile should provide 155 mV. If output is 155 mV or greater, the valve operator will make an audible sound or click when it pulls in. If the valve does not make a sound, replace the valve.

E-The system resistance from the remote switch or thermostat and leadwires should not exceed 1.7 ohms. If it does, reduce the resistance.