Nozzle and Preheater Replacement for a Lanair MX Waste Oil Heater

Lanair Products, LLC

  • Nozzle and Preheater Replacement

Nozzle and Preheater Replacement for a Lanair MX Waste Oil Heater

In this video we will discuss how to replace the fuel nozzle and preheater assembly on a Lanair waste-oil heater.

If you have reason to believe your nozzle or preheater may be clogged, this video should help.

Safety Precautions & Prep

It’s important to follow safety guidelines when working on mechanical, plumbing, and electrical equipment. Only allow qualified technicians to work on your system and ensure that the appropriate personal protective equipment and safe practices are used throughout the work.

Step One

Set the thermostat to its lowest temperature setting and turn the power to the heater off at the building’s circuit breaker.

Step Two

Set the secondary air-pressure regulator to 0 psi and remove the air-supply line from the burner. Disconnect the burner cord and fuel-supply line from the burner, as well. Changing/Servicing the Nozzle

Step One

To change or service the nozzle, remove the nuts mounting the burner to the cabinet and swing the burner away from the cabinet on its hinge.

Step Two

Being mindful not to damage or disturb the electrode tines, remove the nozzle and quad-ring seal. Replacement parts are available from Lanair Customer Service or at

Step Three

When replacing the quad ring, it is important that it seats in the proper position within the preheater and does not become pinched or torn when installing the nozzle. For this reason, do not put the quad ring on the nozzle before installing them. Instead, install the quad ring first and confirm that it is seated correctly before installing the nozzle.

Step Four

With the nozzle and quad ring installed, remount and connect the burner and reattempt the preheater clog test. If replacing or servicing the nozzle has resolved the issue, the heater is ready to return to operation. If the issue persists, replacement of the preheater assembly is necessary.

Step Five

Depending on the system's configuration, it may be easier to work with the burner still mounted to the heater cabinet, or removed and brought to a workbench. Either way, you will need to be positioned to open the burner and look down into it while working and remain safe and stable even with shifting weight distribution.

Step Six

With the power off and the burner cord, air line, and fuel supply all disconnected from the burner, open the burner and locate the preheater assembly within.

Step Seven

Trace the wires from the preheater and make sure the wire nut is on the same side of the burner as the preheater.

Step Eight

Trace the remaining preheater wires to the burner’s main terminal block and preheater switch.

Step Nine

Make a note of where the wires connect, then disconnect them from the burner.

Step Ten

Locate the copper air line, loosen the nuts on both ends, and remove it.

Step Eleven

Next, remove the gauge, fittings, and adjustment screw mounting the preheater to the burner chassis.

Step Twelve

You should now be able to lift and slide the preheater out of the burner.

Step Thirteen

Wipe up any oil or debris that may be present inside the burner chassis.

Step Fourteen

If you have just replaced the nozzle and quad ring, remove them from the faulty preheater and save them for future maintenance.

Step Fifteen

Lay the new preheater assembly into the burner chassis and loosely install the adjustment screw.

Step Sixteen

Adjust the position of the preheater so that the assembly is oriented properly within the burner’s flame tube. If your model came with a calibration tool inside the burner, use it to make the adjustment even easier.

Step Seventeen

When the preheater assembly is correctly positioned, tighten the adjustment screw to fix it in place.

Step Eighteen

Also check the position and gapping of the electrode tines. Refer to the product manual for specifications and adjust the electrodes, if necessary.

Step Nineteen

Continue by reinstalling the fittings, gauge, air line, and wiring to complete the installation of the replacement preheater assembly.

Step Twenty

Remount and connect the burner and reattempt the preheater clog test. If the issue persists, further troubleshooting is necessary. Contact Lanair Technical Support for assistance. If replacing the preheater assembly has resolved the issue, the heater is ready to return to operation.

We hope this video was helpful in servicing your Lanair Waste-Oil Heater …and getting you back to enjoying America’s best value in heating!