Clean and inspect the air tube, including the end cone slots and holes. Verify that the air tube is inserted to the correct position. Reinsert the nozzle assembly into the air tube and secure it in place, making sure it is in the same position that you marked earlier. 7 Burner motor, housing and fan Remove the burner motor and check the burner housing for oil that could indicate a loose fitting, cracked flare or leaking fuel pump seal. If there are oiling points on the motor, lubricate each with 3–4 drops of SAE 20 non-detergent oil. Cooling slots should be clear. Check the motor shaft for end play; if it is excessive, replace the motor. Inspect the burner coupling to be sure it is not worn or stripped. Clean the air inlets and fan using a small brush. After you reinstall the motor, spin the fan a few times to make sure that the motor, fan and pump are moving freely and that everything is properly connected. Check all wires and connections at the burner. 8 Transformer and cad cell Clean and check the transformer bushings and springs. Inspect the ignition wires. Clean the cad cell eye and wires. Make sure the bracket is positioned correctly for good flame sighting. As you close the transformer, be sure the electrodes are making solid contact with the transformer springs and that no wires are being crimped. 9Clean the flue pipe Remove the flue pipe and brush it out, inspect the pipe’s condition, replace it if necessary. Check the draft regulator to be sure it swings freely. If the unit has a stack relay, inspect and clean the helix and the relay contacts. Clean out the chimney base and check for blockages. If there’s an accumulation of broken brick or liner, advise the customer to contact a chimney professional and note this information on your service ticket. If the unit is equipped for power venting, clean and check the fan blower wheel. Oil the motor and check the draft-proving switch. Remember to check and clean the outside hood and exterior mechanism. 10 Clean the heat exchanger & combustion area Remove any baffles and scrub the flue passages, keeping your vacuum hose close to the brush to avoid spreading soot. Look for signs of air or water leaks. Use a soot snorkel to clean the combustion area, being careful not to damage the chamber or target wall. Inspect the condition of the refractory material and repair or replace it as necessary. 11 Replace, seal and fasten Reassemble the unit using furnace cement if necessary to seal any air leaks. Double-check to be sure the flue pipe is connected with sheet metal screws and is supported. 12 Fire the unit and check operation Start the burner, check the appearance of the flame and make sure that there is no impingement. Cycle the burner to check for prompt ignition, smooth operation and clean cut-off. Disconnect the thermostat leads and install a jumper across the T-T terminals to keep the burner running. Check the operation of the high limit control. 13 Efficiency test and adjustments Perform a complete efficiency test and record the readings. Typical readings are: • Smoke: zero to a trace • Draft: Unless the unit is designed for positive pressure, draft over the fire should be approximately -.02" (negative point zero two inches) • CO2: 10½ to 12% • O2: 3 to 6% • Net stack temperature: over 350°F When you have finished adjusting the burner, remember to remove the jumper from the T-T terminals and replace the thermostat wiring. 14 The Heating System The following will vary depending on the type of system you are working on. If there is more than one thermostat, ask the customer to set each one 10° above room temperature. Hot Water System: Check the zone valves and/or circulatorsfor proper operation. If applicable, lubricate the circulator motor and bearing assembly. Check the circulator couplings and motor mounts and the control settings to be sure they’ll provide for proper heating, hot water, and circulator operation. Check the system pressure and the expansion tank. If there is an indirect water heater, check the circulator and control. ICM/May/June 2017 7
ICM May-June 2017
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