How To Replace The Transformer In A Humidifier That Keeps Tripping The Breaker

The humidifier on a furnace adds much needed moisture to the otherwise dry air. The dry air can cause health problems like nose bleeds and allergies, and can also do damage to the inside of your furnace. Problems with the humidifier, however, can end up taking out the whole furnace if the problem in question keeps tripping the unit's breaker. A blown humidifier transformer might be the cause.

Replacing the humidifier transformer isn't hard, but you need to have the knowledge to be certain this is the problem, or you are wasting your time. If you are certain, the fix is a simple one to make.

Things You Need:

  • Owner's manual, optional
  • Screwdriver
  • New transformer with included high voltage wires and wire nuts

Step 1: Remove the Blown Humidifier Transformer

Turn off the power to the furnace at the shut-off switch or by using the breaker in the circuit breaker box.

Locate the blower access panel door on the lower half of the furnace and check to see how the panel door is secured in place. Remove the fasteners by either turning the knobs or using a screwdriver to remove the screws holding the door in place. Lift the door up and off of the furnace and set the door aside.

Locate the transformer inside the furnace. Use a screwdriver to loosen the mounting screws holding the low voltage wires in place, using your owner's manual for a guide if needed. Pull the low voltage wires free of the transformer and allow the wires to dangle in place inside the furnace.

Use your hand to twist off the wire nuts securing the ends of the high voltage wires. Find the strain relief nut holding the transformer in place. Use a screwdriver to help you manually twist off that nut. Pull the entire transformer free of the mounting plate.

Step 2: Install the New Humidifier Transformer

Install the new transformer by first inserting its wires through the hole in the mounting plate, then aligning the new strain relief nut with the mouth of the hole. Secure the transformer by tightening the nut with your hand and the screwdriver.

Match together the colored pairs of high voltage wires, then secure each pair together using the included wire nuts. Attach the dangling low voltage wires to the appropriate terminals on the new transformer. Tighten the screws to secure the wire.

Reposition the blower panel door and secure into place using either your hands to tighten the knobs, or the screwdriver to reattach the screws. Restore power to the unit at the shut-off switch or circuit breaker. Turn the furnace on and check for humidifier functionality. If you still have problems, call in an HVAC services company such as Winters Heating Cooling.