If you notice water leaking from or near your furnace, you need to act quickly. Ignoring it can lead to permanent damage to your furnace, costly repairs, and even flooding in the surrounding area. Identifying the cause early can help you prevent further damage and keep your heating system running efficiently. In this guide, we’ll explore common reasons why high-efficiency furnaces leak water and how you can prevent it.
How High-Efficiency Furnaces Produce Water
Modern high-efficiency furnaces operate differently than older models. Unlike traditional furnaces, which vent hot gases directly outside, high-efficiency furnaces extract additional heat from the combustion process. This process produces steam as a byproduct, similar to how modern car exhaust systems release water vapor.
For your furnace to function properly, this steam must exit your home efficiently. If something disrupts this process, it can result in water leakage around your furnace. Below are the most common reasons your furnace may be leaking water and how to address them.
1. Blocked Furnace Exhaust Vent
Your furnace’s exhaust vent is responsible for releasing steam outside. However, various obstructions can block the vent, causing condensation to build up and leak inside your home. Here are some potential causes of vent blockages:
- Snow or Ice – During winter, heavy snowfall or ice buildup can cover the exhaust vent, preventing proper ventilation. Check for blockages after heavy snowfall and clear the vent if necessary.
- Bee, Wasp, or Bird Nests – In the spring and summer, insects or birds may build nests inside the vent, restricting airflow. If you suspect a blockage, contact a professional to safely remove it.
- Improper Installation – If the vent is not installed with the proper grading, it may sag and collect moisture, leading to leaks. A professional HVAC technician can assess and correct any installation issues.
2. Clogged Condensate Drain Line
High-efficiency furnaces produce condensation, which is drained through a condensate line. This line directs water into a floor drain or, in some cases, a condensate pump that expels the water to the main house drain, a laundry sink, or directly outside. If the floor drain or condensate drain line becomes clogged, water can back up and leak around your furnace.
Signs of a Clogged Condensate Line:
- Pooling water near your furnace
- Gurgling noises coming from the drain
- Visible buildup or mold around the drain line
How to Fix It:
- Inspect the Drain Line – Check for visible debris or blockages. A simple flush with warm water and mild detergent can help clear minor clogs.
- Unclog the Drain – If the clog persists, using a wet/dry vacuum to clean out debris from the floor drain can be effective; and if the drain is blocked, a drain cleaning professional may be needed.
- Regular Maintenance – Cleaning the condensate line annually can prevent future blockages and leak. This is done by your plumber/gas fitter during an Annual Furnace Service.
Regular maintenance is crucial for preventing such issues. Learn more about the importance of annual furnace service in our detailed furnace service guide.
3. Frozen Condensate Line
During colder months in Surrey and Langley, BC, and the surrounding areas, low temperatures can cause the condensate line to freeze. When this happens, water cannot drain properly, leading to leaks inside your home.
How to Prevent Freezing:
- Ensure Proper Insulation – Wrapping the condensate line in insulation can help prevent freezing during winter.
- Keep the Area Warm – If possible, keep your furnace room above freezing temperatures to prevent ice buildup.
- Use a Heat Tape – In extreme cold, a heat tape can be applied to the condensate line to keep it from freezing.
When to Call a Professional
While some furnace leaks can be resolved with basic maintenance, persistent water issues may require the expertise of an HVAC professional. If you’ve checked for blockages, cleared the drain line, and ensured proper installation but still notice leaks, it may indicate a more serious problem with your furnace’s internal components, condensate pump, or vent.
At John Sadler Plumbing & Heating, we provide expert furnace repair and maintenance services in Surrey and Langley BC, and the surrounding areas. Our team can quickly diagnose and resolve furnace leaks, ensuring your home stays warm and dry.
Need Help with a Leaking Furnace?
Give us a call today or schedule an appointment online! Our experienced technicians are ready to help keep your furnace running smoothly.
