PVI Industries FIREPOWER PV500-9 User Manual

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PVI Industries FIREPOWER PV500-9 User Manual

PVI FIREPOWERâ GAS BURNER

TYPICAL CONSTRUCTION

Figure 9-1

1.

Burner housing

15.

Air switch

29.

Orifice location *

2.

Air intake

16.

Door assembly *

30.

Electrode retaining bracket

3.

Oil pump opening plug

17.

Flame sensing electrode

31.

Burner cover

4.

Mounting flange

18.

Ignition electrode

32.

Burner sight glass

5.

Mounting flange gasket

19.

Ignition transformer

33.

Air shutter

6.

Blast tube screw

20.

On-off switch *

34.

Union

7.

Blast tube

21.

1/4” NPT pressure port plug

35.

Flame safeguard control

8.

Nozzle assembly

22.

Motor mounting plate *

36.

Flame cone

9.

Nozzle mount bolt

23.

Motor relay or starter *

37.

Manual gas valve

10.

Air inlet cone

24.

Pressure plate

38.

Lifting eye bolt

11.

Air screen

25.

Primary gas ports

39.

Power connector

12.

Fan wheel

26.

Secondary gas ports (gas spider)

40.

Manifold test port

13.

Motor, 3450 rpm CWSE rotation

27.

Gas regulator

 

* On some models

14.

Air nipple

28.

Gas valve

 

PV500-9 04-2000

 

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Section 9

POWER GAS BURNER START-UP (Refer to Figure 9-1 to identify burner parts)

1.Remove the enclosure panel cover on the water heater or boiler to expose the control circuit. Located on the back side of this cover is a wiring diagram of the unit. This diagram will show the controls used in our circuitry.

2.Visually check to be sure all components are intact and no damage has occurred during transit.

3.Check all connections within the control cabinet. A loose connection on a component could cause intermittent shutdowns.

4.Some burners will use direct spark ignition. They may use a single gas pressure regulator and gas valve or multiple valves and regulators. On a call for heat, the motor starts, the gas primary control is energized, and after a short delay (pre-purge), the gas valve(s) opens and ignition should occur. Some burners have longer pre-purge periods. On a call for heat, the control is energized which starts the motor and begins a purge sequence. On completion of the purge cycle, the gas valve(s) opens and ignition occurs.

5.Remove flame safeguard control from its base. Check connections in the control mounting base. Again, loose connections can cause nuisance shutdowns. Also check the time card or programmer, when applicable, for good connection.

NOTE: Always secure gas lines and tag “Out of Service” before servicing burner nozzle or electrodes.

6.Pull the nozzle assembly to check the flame and ignition electrodes. This is done by first removing the burner cover, exposing the nozzle assembly.

7.The L-Series burner must be removed from the heater and the blast tube removed to access the electrodes. The electrodes may be accessible by removing the nozzle assembly on larger burners. Free the nozzle assembly from the gas train by breaking the unions on the gas lines. Some models will use an orifice that is installed in these unions. Retain for re-use.

8.Next, remove the four bolts that hold the nozzle assembly to the burner housing. Once the nozzle assembly is free, pull it back slightly and remove the wires going to the flame and ignition rod. The easiest method of removing the nozzle assembly is to rotate it 90° upward and tilt slightly forward while working it towards you (see Figure 9-2). Be careful not to damage the electrodes.

9.With the electrodes exposed, check them for the proper settings as called for in Figure 9-3. Also check for any hairline cracks in the insulators. Should replacement of burner electrodes be required, certain procedures must be followed. In all cases, removal of the electrodes is accomplished by loosening the electrode mounting bracket retaining screw. Draw the electrodes out of the nozzle assembly through the

holes in the pressure plate.

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10.Inspect the electrodes for cracked ceramics or loose retaining studs that hold the wire within the ceramic. Using supplied metric Allen wrench, loosen one or two pressure plate retaining screws so that the plate rotates freely on nozzle hub. Push plate towards the nozzle assembly gas spider to ensure it remains fully back and level. Do not re-tighten retaining screws at this time. Select the proper pressure plate hole in which to place each electrode and insert the electrode through the hole, retaining stud end first. Place electrodes in the electrode mounting bracket between the mount and the retaining bracket.

11.Tighten electrode mounting bracket screw slightly until electrode ceramics are seated firmly and completely in mounting bracket without gaps between ceramics and mounting bracket at the bearing faces.

NOTE: Electrodes may have a high temperature, electrically insulating tape around them. The tape is designed to cushion the ceramic insulators in the mounting bracket, but is not absolutely necessary, and may be removed if it interferes with the positioning of the electrodes.

12.Ensure electrodes are loose enough to be rotated and that they will slide back and forth in the mounting bracket with firm finger pressure.

13.While ensuring the pressure plate is in the previously described position, measure and set electrodes according to Figure 9-3. After the gaps and settings are complete, fully tighten the electrode mounting bracket retaining screw. Do not overtighten or the insulation may crack.

CAUTION: Electrodes may shift while tightening the screw due to rotation of the upper electrode mounting bracket. Holding down on this bracket while tightening the screw will stop this from happening.

NOTE: The pressure plate may rotate on the nozzle hub as the electrodes seek their position during the tightening of the electrode mounting bracket retaining screw. This is desirable to prevent the electrodes from binding and not seating properly in the mounting bracket. The electrode ceramics will crack, causing ground faults in the circuit if this condition exists.

14.After complete mounting and positioning of the electrodes is accomplished, rotate the pressure plate so that no portion of the plate touches the electrode ceramics at the holes the electrodes pass through in the plate (ream holes slightly larger if needed to obtain

Section 9

POWER GAS BURNER START-UP (Con’t)

clearance). Ensure plate is seated firmly against the gas spider and tighten the plate retaining screws. Recheck electrode setting as to gap and position.

15.Replace nozzle assembly; be sure to connect the flame and spark rod wires before installing nozzle assembly fully into blast tube. Check to be sure connectors on the ends of the flame and spark rod wires have a good contact. Look for properly stripped wire ends. Be sure connectors are firmly attached to the flame and ignition rod ends. Insulating boots can give a false feeling of proper seating. BE CAREFUL NOT TO MOVE ELECTRODES. Be careful not to bump electrodes Check fan wheel for free rotation.

16.Reinstall orifices in unions (if required). Reinstall burner cover.

17.Connect a test meter to the control for reading the flame response signal.

NOTE: Some controls read the flame signal in micro amps and some in volts DC. The TFM series control has two terminals marked for reading volts DC. The S89 control uses a micro amp signal for measuring flame strength. For this control, a meter must be hooked in series with the flame rod wire. Disconnect the leadwire at the S89 sensor terminal. Connect the positive lead of the meter to the quick-connect sensor terminal on the S89 and the negative lead to the free end of the sensor leadwire.

18.Be sure the tank is filled with water. Once the burner is reassembled, two devices to read pressure, preferable U-tube manometers, will be needed to read gas pressures. Connect one to read the inlet pressure of the burner. This is the pressure measured before all components in the gas train. The manometer must stay connected throughout the testing, as the inlet pressure must be monitored during the firing of the burner. Record static pressure. It must not exceed 14” W.C. for burners with inputs through 3,200,000 Btu/h. For inputs above 3,200,000 Btu/h, refer to the appliance date plate for the correct maximum inlet pressure Pressures above this could cause damage to the diaphragm in the gas valve or pressure regulator.

19.Burners with pilot:

A.Connect the manometer to the manifold test port at the shutoff valve closest to the burner. Turn the main gas shutoff valve off. Set the air shutter as shown on the tag attached to the gas train, (see Figure 9-4 and 9-5). This may not be the exact setting you end with, but it is a good starting point. Turn the unit on using the rocker switch on the side of the control enclosure assembly and the toggle switch on the burner. If the operating control switches are closed, the burner should come on and pre-purge begin.

B.If nothing happens, check the control to be sure it is not in the tripped position and reset it by pushing

PV500-9 04-2000

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flame safeguard reset button. The burner should prepurge for not longer than thirty seconds. The TFM series control will have either an MT30-4, MT30-10 or MT12-5 time card. The “30 indicated a 30-second purge time and the “4”, “5” or “10” indicated a 4- second, 5-second, or 10-second trial for ignition period, commonly called TFI.

When the blower motor starts, the air switch which proves air flow should close and terminal 6 will be powered. This starts the pre-purge timing sequence. After purging is complete, terminal 3 or 4 on the TFM control are energized. Terminal 3 energizes the pilot valve and terminal 4 energizes the ignition transformer. At this time, the pilot is established. The VDC reading on thermometer should read a steady 14-17 VDC for a TFM control. Each different control will have the required flame response signal stamped on it. This is the minimum for it to properly operate. If the pilot fails to light during the initial ignition period, it is probably due to air in the line. The control will lock out. Wait one minute and push the flame safeguard reset button to restart burner and begin the purge cycle again.

Now, set the pilot pressure (measured downstream of gas valve) at the pressure shown on the tag attached to the gas train. Next, open the main gas valve slowly. Set manifold pressure at the pressure shown on the tag attached to the gas train. Do not screw the adjusting nut of the regulator in past the point where no further increase in manifold pressure is noted. Check the incoming pressure with the burner running. This is recorded as inlet flow pressure.

Our standard flow pressure requirements are:

a.5” W.C. with 8” W.C. flow on burners with inputs through 1,600,000 Btu/h.

b.8” W.C. with 11” W.C. flow on burners with inputs from 2,000,000 Btu/h through 3,200,000 But/h.

c.For inputs above 3,200,000 Btu/h, refer to the tag attached to the gas train for the correct inlet pressures.

C.If the required manifold cannot be reached, check the inlet pressure. It should be a minimum of that shown above with the burner running on full input. It is important that the incoming pressure does not fall below these minimums or nuisance control lockouts could occur.

NOTE: Where low gas pressure is a problem, special arrangements may have been made to fire the burner with reduced pressure. The appliance data decal will reflect this information.

Section 9

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