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

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flame safeguard reset button. The burner should pre- purge 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