Lennox Furnace Condensate Trap Replacement

Single condensate drain line for a Lennox C33 cooling coil and SLP98 FAU
Single condensate drain line for a Lennox C33 cooling coil and SLP98 FAU from hvac-talk.com

Lennox Furnace Condensate Trap Replacement – 2023


In this article, we will discuss the process of replacing the condensate trap in a Lennox furnace. The condensate trap plays a crucial role in the efficient functioning of the furnace by collecting and removing the condensate produced during the heating process. Over time, the trap may become clogged or damaged, necessitating its replacement.

Why is the condensate trap important?

The condensate trap prevents the condensate from entering the furnace’s blower motor and other sensitive components. If the trap is not functioning properly, the condensate can cause damage and affect the overall performance of the furnace. Regular maintenance, including trap replacement when necessary, is essential to ensure the furnace operates optimally.

Step 1: Turn off the power

Prior to starting any work on the furnace, it is crucial to turn off the power supply. Locate the electrical disconnect switch near the unit and switch it off. This step ensures your safety and prevents any accidental damage to the furnace.

Step 2: Locate the condensate trap

The condensate trap is typically located near the bottom of the furnace. Consult the furnace’s manual or look for a plastic or metal box with hoses connected to it. This box is the condensate trap, and it may be secured with screws or clips.

Step 3: Disconnect the hoses

Using a pair of pliers or a wrench, carefully loosen the hose clamps that secure the hoses to the condensate trap. Once the clamps are loose, gently pull the hoses off the trap. Be cautious as the hoses may contain residual condensate.

Step 4: Remove the condensate trap

If the trap is secured with screws, use a screwdriver to remove them. Alternatively, if it is secured with clips, carefully release the clips to detach the trap from the furnace. Take note of the trap’s orientation for easy installation of the new trap.

Step 5: Install the new condensate trap

Take the new condensate trap and align it with the mounting holes or clips on the furnace. If there are screws, secure them tightly with a screwdriver. If there are clips, ensure they are properly engaged to hold the trap in place.

Step 6: Reconnect the hoses

Slide the hoses onto the appropriate connectors on the new condensate trap. Use hose clamps to secure the hoses tightly, ensuring a proper seal. This prevents any leaks or condensate from escaping the trap.

Step 7: Restore power and test

Now that the new condensate trap is in place and the hoses are securely connected, it’s time to restore power to the furnace. Turn on the electrical disconnect switch and wait for the furnace to power up. Monitor the operation of the furnace and check for any signs of leaks or issues with the trap.

Step 8: Regular maintenance

It’s important to remember that the condensate trap requires regular maintenance to ensure proper functioning. Cleaning the trap periodically and inspecting it for any signs of damage or clogs are essential. If you notice any issues, such as leaks or blockages, it’s best to consult a professional HVAC technician for assistance.


Replacing the condensate trap in a Lennox furnace is a relatively straightforward process. With the right tools and precautions, you can easily replace the trap and ensure the furnace operates efficiently. Remember to follow the steps outlined in this article and perform regular maintenance to keep your furnace in optimal condition.