In 1990, when I started as a service technician, I had the privilege of working on literally thousands of these Lennox Gas Furnaces. If you are a technician this is a must see video on where these Lennox curved heat exchangers fail.

Remember to always check the following when and if you find a failed heat exchanger on a Lennox furnace or any other furnace with a cracked heat exchanger.

• Static Duct Pressure
• Filter size
• Evaporator coil
• Number of supplies and returns
• Gas Pressure
• Delta T
• Venting
• Draft
• Perform a combustion analysis
• Check for gas leaks