resideo Millivoltage combination gas controls Installation Guide

VS820 and VS821
MILLIVOLTAGE COMBINATION GAS CONTROLS
INSTALLATION INSTRUCTIONS

APPLICATION

The VS820 and VS821 are used on gas-fired, standing pilot appliances with 750 mV self-powered control systems. The gas controls include a manual gas valve, safety shutoff, single millivoltage automatic operator, and pressure regulator.
Refer to Table 1 for capacity ratings and Table 2 for pressure regulators and temperature ratings. Separate models are available for natural and LP gas.
Power for the gas control and the control system is provided by a 750 mV Powerpile generator.

Table 1. VS820 and VS821 Pipe Size and Capacity Ratings.

Model

|

Inlet x Outlet

|

Reducer Fittings b

---|---|---

Pipe Size

|

Capacity a

|

Size

|

Capaccity

cfh| m 3 /hr| cfh|

m 3 /hr

VS821| 1/2 x 3/8| 110| 3.1| –| –| –
VS820| 1/2 x 1/2| 225| 6.4| –| –| –
1/2 x 3/4| 250| 7.1| 3/4 x 1/2| 225| 6.4
1/2 x 3/8| 110| 3.1
3/4 x 3/4| 335| 9.5| 3/4 x 1/2| 250| 7.1
3/4 x 1/2| 225| 6.4

aCapacity is based on 1000Btuh/ft , 0.64 sp gr natural gas at 0.25 kPa pressure drop]. Use conversion factors in Table 3 to convert for other gases. 3, 0.64 sp gr natural gas at 1 in. wc pressure drop [37.3 MH/m 3
bReducer fittings must be obtained locally.

Table 2. Pressure Regulator and Temperature Ratings.

Model|

Pressure Type

| Regulator Model|

Temperature Rating

---|---|---|---
°F|

°C

VS820A,H| Standard| V5306A| 32 to 175| 0 to 79
VS821A
VS820C, VS821 C| Step| V5307A
VS820M| Standard| V5306A| -40 to 175| -40 to 79
VS820P| Step| V5307B

Table 3. Gas Capacity Conversion Factors.

Type of Gas

| Specific Gravity|

Multiply Listed Capacity By

---|---|---
Manufactured| 0.60| 0.516
Mixed| 0.70| 0.765
Propane| 1.53| 1.62

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 these instructions and on the product to make sure the product is suitable for your application.
3. Make sure the installer is a trained, experienced service technician.
4. After completing the installation, use these instructions to check product operation.

WARNING
FIRE OR EXPLOSION HAZARDS 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 the dangerous accumulation of fuel gas, turn off the gas supply at the appliance service valve before starting the installation and perform Gas Leak Test following installation.
3. Do not bend pilot tubing at control or at pilot after compression fitting has been tightened. Gas leakage at the connection fitting may result.
4. Always install sediment traps in the gas supply line to prevent contamination of gas control.
5. Do not force the gas control knob. Use only your hand to turn the gas control knob. If the knob will not operate by hand, the control should be replaced by a qualified service technician.
   Force or attempted repair may result in fire or explosion.

CAUTION
Never apply a jumper across (or short) valve coil terminals. This may burn out the thermostat heat anticipator.
IMPORTANT
These gas controls are shipped with protective seals over inlet and outlet tappings. Do not remove seals until ready to connect piping. Follow the appliance manufacturer’s instructions if available; otherwise, use the instructions provided below as a guide.
Choose Location
Do not locate the combination gas control where it may be affected by steam cleaning, high humidity or dripping water, corrosive chemicals, dust or grease accumulation, or excessive heat. To ensure proper operation, follow these guidelines:

• Locate in a well-ventilated area.
• Mount is high enough above the cabinet bottom to avoid exposure to flooding or splashing water.
• Ensure that the ambient temperature does not exceed the ambient temperature ratings for each component.
• Cover if the appliance is cleaned with water, steam, or chemicals or to avoid dust and grease accumulation.
• Avoid locating where exposure to corrosive chemical fumes or dripping water is likely.

Mount the combination gas control in the appliance vestibule on the gas manifold. If this is a replacement application, mount the gas control in the same location as the old control. Make sure the total control circuit wire length does not exceed 30 ft [9.2 m] of 2-wire, 18 gauge cable or 50 ft [15.3 m] of 2-wire, 16 gauge cable.

Inlet and Outlet Adapters
If adapters are needed, prepare control as follows:

1. Remove seal over control inlet or outlet.

2. Apply a moderate amount of good quality pipe compound adapter, leaving two end threads bare.
   Refer to Fig. 1. On LP installation, use compound resistant to LP gas. Do NOT use Teflon tape.

3. Insert adapter in control and thread carefully until tight.

Fig. 1. Use a moderate amount of pipe compound.

Install Piping to Control

All piping must comply with local codes and ordinances or with 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. If tubing is used, make sure the ends are square, deburred, and clean. All tubing bends must be smooth and without deformation.
2. Run pipe or tubing to control. If tubing is used, obtain a tube-to-pipe coupling to connect tubing to the control.
3. Install sediment trap in the supply line to the gas control. Refer to Fig. 2.

ALL BENDS IN METALLIC TUBING SHOULD BE SMOOTH.
CAUTION: SHUT OFF THE MAIN GAS SUPPLY BEFORE REMOVING THE END CAP TO PREVENT GAS FROM FILLING THE WORK AREA. TEST FOR GAS LEAKAGE WHEN INSTALLATION IS COMPLETE.
M3077C

Fig. 2. Sediment trap installation.

Install Control

1. This control can be mounted 0-90 degrees, in any direction, from the upright position of the gas control knob, including vertically.

2. Mount the control so the gas inlet is on the end with a projecting wrench boss. Refer to Fig. 3 and 4.
   |
   ---|---

3. Thread pipe the amount shown in Table 4 for insertion into control. DO NOT THREAD PIPE TOO FAR.
   Valve distortion or malfunction may result if the pipe is inserted too deeply.
   Table 4. NPT Pipe Thread Length.
   Pipe Size| Thread Pipe This Amount| Maximum Depth Pipe Can Be
   Inserted Into Control
   ---|---|---
   8-Mar| 16-Sep| 8-Mar
   2-Jan| 4-Mar| 2-Jan
   4-Mar| 13/16| 4-Mar

4. Apply a moderate amount of good quality pipe compound (DO NOT use Teflon tape) to pipe or coupling only, leaving two end threads bare. On LP installations, use compound resistant to LP gas.
   Refer to Fig. 1.

5. Remove seals over control inlet and outlet, if necessary.

6. Connect pipe or coupling to control inlet and outlet.
   To tighten inlet and outlet connections, use a wrench on wrench boss only. Refer to Fig. 3 and 4. If tubing is used, connect tubing to coupling.

Pipe Size| Thread Pipe This Amount| Maximum Depth Pipe Can Be
Inserted Into Control
---|---|---
8-Mar| 16-Sep| 8-Mar
2-Jan| 4-Mar| 2-Jan
4-Mar| 13/16| 4-Mar

Connect Pilot Gas Tubing

1. Cut the tubing to the desired length and bend as necessary for routing to the pilot burner. Do not make sharp bends or deform tubing. Do not bend tubing at control after
   compression nut has been tightened, as this may result in a gas leakage at the connection.

2. Square off and remove burrs from the end of the tubing.

3. Unscrew brass compression fitting from the pilot outlet (Fig. 3 or 4). Depending on the gas control model, the fitting supplied may be for 1/8 or 1/4 in.
   tubing. Slip the fitting over the tubing and slide out of the way.
   NOTE: When replacing a control, also replace the compression fitting.
   Never use the old compression fitting as it may not provide a gas-tight seal. Refer to Fig.5
   

4. Push tubing into the pilot gas tapping on the outlet end of the control until it bottoms. While holding tubing all the way in, slide fitting into place and engage threads. Turn until finger tight. Then tighten one more turn with a wrench. Do not overtighten.

5. Connect another end of the tubing to the pilot burner according to the pilot burner manufacturer’s instructions.

Wiring
IMPORTANT

1. Since the entire control system is powered by the millivoltage generated by the Powerpile generator, clean and scrapes all wires before connecting. Solder and tape all necessary splices using rosin flux to prevent corrosion.
2. Control circuit cable length must not exceed 30 ft [9 m] of 2-wire, 18 gauge cable, or 50 ft [15 m] of 2-wire, 16 gauge cable.

Follow appliance manufacturer’s wiring instructions, if available, or use general instructions provided below.
Where instructions differ, follow appliance manufacturer instructions.
All wiring must comply with local electrical codes and ordinances or with the National Electrical Code (ANSI/NFPA 70), whichever applies.
Never connect these millivoltage controls to line voltage or to a transformer.
To prevent electrical shock or equipment damage, disconnect the power supply before making wiring connections.

1. After the Powerpile generator is installed in the pilot burner, the route generator leads to gas control.
2. Connect lead to gas control terminals labeled PP.
3. Connect thermostat leads as shown in Fig. 6 or 7.

|
---|---

1 COMBINATION SCREW, 1/4 INCH QUICK-CONNECT TERMINALS (4).
2 POWER PILE OPERATOR COIL (INTERNAL WIRING).
3 MUST BE APPROVED SAFETY-CIRCUIT WIRING.
4 PILOTSTAT POWER UNIT COIL (INTERNAL WIRING.)
5 ECO, IF USED.
M36108
Fig. 7. Typical wiring connections for gas control with the four-terminal operator.

STARTUP AND CHECKOUT

WARNING
FIRE OR EXPLOSION HAZARD CAN CAUSE PROPERTY DAMAGE, SEVERE INJURY, OR DEATH Do not force the gas control knob. Only use you

1. hand to push down or turn the gas control knob. Never use any tools.
2. If the gas control knob will not operate by hand, or if the knob stays depressed after it is released, the control should be replaced by a qualified service technician.
3. Perform the gas leak test described below any time work is done on a gas system.

Gas Knob Control Settings
The gas control knob has three settings:

• OFF prevents pilot and main gas flow through the control.
• PILOT permits gas flow to the pilot burner as long as the gas control knob is held down or the generator current is above the power unit dropout value.
• ON permits gas flows into the combination gas control body. Pilot gas is controlled as in the PILOT position. Main burner gas is controlled by the thermostat and automatic valve operator.

Perform Gas Leak Test
WARNING
FIRE OR EXPLOSION HAZARDS CAN CAUSE PROPERTY DAMAGE, SEVERE INJURY, OR DEATH
Check for gas leaks with soap and water solution any time work is done on a gas system.
Gas Leak Test:

1. Pain pipe connections upstream of gas control with rich soap and water solution. Bubbles indicate a gas leak.
2. If the leak is detected, tighten pipe connections.
3. Stand clear of the main burner while lighting to prevent injury caused by hidden leaks which could cause flashbacks in the appliance vestibule. Light main burner.
4. With the main burner in operation, paint pipe joints (including adapters), and control inlet and outlet with rich soap and water solution.
5. If another leak is detected, tighten adapter screws, joints, and pipe connections.
6. Replace part of leak can’t be stopped.

Light Pilot

1. Turn gas control knob clockwise to OFF. Wait five minutes to dissipate any unburned gas. Sniff around the appliance near the floor. Don’t relight the pilot if you smell gas.
2. Turn the gas control knob counterclockwise to PILOT. Push down and hold the knob while you light the pilot the burner.
3. Hold the gas control knob down for about one minute, then release. If the pilot goes out, turn the gas control knob clockwise to OFF. Repeat steps 1-3.
4. Release gas control knob. If the pilot remains lit, turn counterclockwise to ON.

Adjust to Flame
The pilot flame should envelop 3/8 to 1/2 in. [10 to 13 mm] of the tip of the generator. Refer to Fig. 8.
To adjust:

1. Remove pilot adjustment cover screw. Refer to Fig. 2 or 3.
2. Turn the inner adjustment screw clockwise to decrease or counterclockwise to increase the pilot flame.
3. Always replace cover screw after adjustment and tighten firmly to ensure proper operation.

Turn on Main Burner
Follow instructions provided by the appliance manufacturer or turn up the thermostat to call for heat. Check and Adjust Gas Input to Main Burner
CAUTION

1. Do not exceed input rating stamped on appliance nameplate, or manufacturer’s recommended burner orifice pressure for size orifice(s) used. Make certain the primary air supply to the main burner is properly adjusted for complete combustion. Follow appliance manufacturer’s instructions.
2. IF CHECKING GAS INPUT BY CLOCKING GAS METER: Make certain there is no gas flow through the meter other than to the appliance being checked. Other appliances must remain off with their pilots extinguished (or their consumption must be deducted from the meter reading). Convert flow rate to Btuh as described in form 70- 2602, Gas Controls Handbook, and compare to the Btuh input rating on the appliance nameplate.
3. IF CHECKING GAS INPUT WITH MANOMETER:
   Make certain gas control is in PILOT position before removing outlet pressure tap plug to connect manometer (pressure gauge). Also, turn the gas control knob back to  ILOT when removing the gauge and replacing the plug. Before removing the inlet pressure tap plug, shut off the gas supply at the manual valve in the gas piping to the appliance or, for LP, at the tank. Also, shut off the gas supply before disconnecting the manometer and replacing the plug. Repeat Gas Leak Test at the plug with the main burner operating.

VS820A; VS821A (Standard Pressure Regulator)

1. Check the manifold rating listed on the appliance nameplate. Gas control outlet pressure should match the nameplate.

2. With the main burner operating, check gas control outlet gas flow using the meter clocking method or pressure using a manometer connected to the outlet pressure tap on the gas control. Refer to Fig. 2 or 3.

3. If necessary, adjust the pressure regulator to match the appliance rating. Refer to Table 5 for factory set nominal outlet pressure and adjustment range.
   a. Remove pressure regulator adjustment cap screw.
   b. Using a screwdriver, turn the inner adjustment screw clockwise to increase or counterclockwise to decrease gas pressure to burner.
   c. Always replace the cap screw and tighten firmly to ensure the system functions properly.

4. If desired outlet pressure or flow rate cannot be achieved by adjusting the gas control, checking gas control inlet pressure using a manometer at the inlet pressure tap. If inlet pressure is in the nominal range (refer to Table 5), replace gas control. Otherwise, take the necessary steps to provide proper gas pressure to the control.

VS820C, P; VS821C (Step-Opening Pressure Regulator)

1. Check the full rate manifold pressure listed on the appliance nameplate. Gas control full rate outlet pressure should match this rating.

2. With the main burner operating, check gas control outlet flow rate using the meter clocking method or outlet pressure using a manometer connected to the outlet pressure tap on the control. Refer topic. 3 or 4.

3. If necessary, adjust the pressure regulator to match the appliance rating. Refer to Table 5 for factory set nominal outlet pressure and adjustment range.
   a. Remove pressure regulator adjustment capscrew.
   b. Using a screwdriver, turn the inner adjustment screw clockwise to increase or counterclockwise to decrease gas pressure to burner.
   c. Always replace the cap screw and tighten firmly to ensure the system functions properly.

4. If desired outlet pressure or flow rate cannot be achieved by adjusting the gas control, check gas control inlet pressure using a manometer upstream of the gas control. If inlet pressure is in the nominal range (refer to Tables 5 and 6), replace gas control.
   Otherwise, take the necessary steps to provide proper gas pressure to the control.

5. Carefully check burner light off at step pressure.
   Make sure burner lights smoothly and without a flashback to the orifice. Make sure all ports remain lit.
   Cycle burner several times, allowing at least 30 sec. between cycles for the regulator to resume step function. Repeat after allowing the burner to cool.
   Readjust full rate outlet pressure if necessary to improve light off characteristics.

Table 5. Pressure Regulator Specification Pressures in. wc.

Model

| Type of Gas| Nominal Inlet
Pressure Range| Factory Set Nominal Outlet Pressure|

Setting Range

---|---|---|---|---
Step| Full Rate| Step|

Range

VS820A,H,M| NAT| 5.0-7.0| | 3.5| –| 3-5
VS821A| LP| 12.0-14.0| | 11.0| –| 8-12
VS820C,P| NAT| 5.0-7.0| 0.9| 3.5| None| 3-5
VS821C| LP| 12.0-14.0| 2.2| 11.0| None| 8-12

Check and Safety Shutdown Performance
WARNING
FIRE OR EXPLOSION HAZARDS CAN CAUSE PROPERTY DAMAGE, SEVERE INJURY, OR DEATH
Perform the safety shutdown test anytime work is done on a gas system.

1. Place gas control knob in PILOT position. The main burner should go out and the pilot should remain lit.
2. Extinguish pilot flame. Pilot gas flow should stop within 2-1/2 minutes. Safety shutoff of pilot gas proves complete shutdown since safety shutoff valve blocks the flow of gas to main burner and pilot.
3. Relight pilot burner and turn the gas control knob to ON.
4. Set the thermostat to call for heat and observe the appliance through one complete cycle to make sure it operates as intended.

SERVICE
CAUTION
Never apply a jumper across (or short) valve coil terminals. This may burn out the thermostat heat anticipator.
IMPORTANT
Allow 30 seconds after shutdown before energizing the step-opening model to ensure light off at step pressure.
If the Pilot Light Will Not Light

1. Make sure the main gas supply valve is open and the pilot gas supply line is purged of air.
2. Attempt to light pilot following the procedure in “Light Pilot” on page 4.
3. Then if:
   a. Pilot gas adjustment screw is closed, readjust pilot flame. Refer to page

4. b. Compression fitting has a gas leak, replace old compression fitting or tighten new one. Refer to page 3.
   c. Pilot burner tubing or orifice is clogged, replace combination gas control. Refer to page 1.

If Pilot Goes Out when Gas Control Knob is Released

1. Make sure the gas control knob is held for at least one minute to allow the generator time to heat.

2. Check pilot flame adjustment, refer to page 4.

3. Check the wiring between the generator and the valve operator in the gas control.

4. Make sure the jumper between the valve operator and power unit is secure and connections are clean. Connection to power unit should be tightened 1/4 turn beyond finger tight.

5. If the pilot still goes out, measure the open circuit output voltages.
   Compare to acceptable range charts in the generator specifications or in theGas Controls Handbook. Replace the generator if voltages are outside the acceptable range.

6. Check power unit resistance. If above 11 ohms, replace gas control.

If Main Burner Will Not Come On With Call For Heat

1. Make sure the gas control knob is in the ON position.
2. Adjust the thermostat several degrees above room temperature.
3. Disconnect lead wires to lower left TH terminal and lower right PP terminal to isolate valve operator coil from the balance of the circuit. Measure resistance of the coil. If the coil is not 2 ohms ±10 percent, replace Valve.
4. Measure the open generator circuit output voltages and compare to acceptable range charts in the generator specifications or in the Gas Controls
   Handbook. Replace the generator if voltages are outside the acceptable range.

If Burner is Overfiring
Adjust pressure regulator to correct pressure. If the regulator cannot be adjusted and supply pressure is in the normal range, replace complete gas control.
Instructions to the Homeowner
WARNING
FIRE OR EXPLOSION HAZARDS CAN CAUSE PROPERTY DAMAGE, SEVERE INJURY, OR DEATH
Follow these warnings and lighting instructions exactly.

1. Before lighting, smell all around the appliance area for gas. If the appliance uses LP (bottled) gas, also be sure to smell next to the floor because LP gas is heavier than air. If you smell gas, immediately shut off the manual valve in the gas piping to the appliance. ON LP SYSTEMS, AT THE TANK. Do not try to light any appliances in the house. Do not touch electrical switches or use the phone. LEAVE THE BUILDING and call your gas supplier from a neighbor’s house. If your gas supplier can not be reached, call the fire department.
2. Do not force the gas control knob on the appliance. Use only your hand to push downturn the gas control knob. Never use any tools the gas control knob will not operate by hand the control should be replaced by a qualified service technician. Force or attempted repair may result in fire or explosion.
3. The control must be replaced if it has been flooded with water.
4. The control is a SAFETY DEVICE. It must be replaced in case of any physical damage, tampering, bent terminals, missing or broken parts, stripped threads, or evidence of exposure to heat.

IMPORTANT
Follow the appliance manufacturer’s instructions. The information below will assist in typical control applications, but the specific controls may require a special manufacturer
instructions.
Lighting the Pilot Burner
STOP: Read the warning at the left.
This appliance has a pilot burner which must be lit by hand. If the pilot flame has gone out, follow these instructions exactly.

1. Set the thermostat to the lowest setting.

2. Turn off all electric power to the appliance.

3. Remove the control access panel.

4. Push in gas control knob (refer to Fig. 3 or 4) slightly and turn clockwise to OFF.
   NOTE: Knob cannot be turned from PILOT to OFF unless knob is pushed in slightly. Do not force.

5. Wait five (5) minutes to clear out any gas. If you then smell gas, STOP! Follow item 1 in the Warning above. If you don’t smell gas, go to the next step.

6. Remove the pilot access panel located below and behind the gas control unit.

7. Find the pilot—follow metal tube from gas control. The pilot is between the two-burner tubes behind the pilot access panel.

8. Turn the knob on gas control counterclockwise to PILOT.

9. Push in the control knob all the way and hold in. Immediately light the pilot with a match. Continue to hold the control knob in for about one (1) minute after the pilot is lit. Release the knob and it will pop back up. The pilot should remain lit. If it goes out, repeat steps 5-10.

10. Replace the pilot access panel.

11. Turn gas control knob counterclockwise to ON.

12. Replace the control access panel.

13. Turn on all-electric power to the appliance.

14. Set the thermostat to the desired setting.

To Turn Off Appliance
VACATION SHUTDOWN—Turn gas control knob clockwise from ON to PILOT. The pilot will remain lit, ready for return to normal service without relighting.
COMPLETE SHUTDOWN—Push in the gas control knob slightly and turn clockwise to OFF. Do not force.
Both pilot and main burner are shut off. Follow the lighting procedure above to resume normal operation.

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1-800-468-1502
95-6994EF—03 M.S. Rev. 01-21
Printed in the United States
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