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Leaking Furnace

Why is My Furnace Leaking Water?

Winter is headed our way, so you know what that means. Soon, you'll need to fire up your furnace. But if you've already flipped the switch only to find water leaking from your furnace, there are several reasons why this is happening. While some cases are minor, others may indicate a major issue, which needs immediate attention.


Newer furnaces are far more energy efficient than older units. Since newer systems are designed to cool the exhaust away from the unit itself, it’s not uncommon to see an increase in condensation. Usually, it collects at the bottom of the furnace, leading homeowners to think their furnace is leaking. If you have a newer model, this is probably the issue. However, if you have an older furnace, your flue pipe might be the wrong size and not functioning properly.

Heat Exchanger

A malfunctioning heat exchanger inside your HVAC is one of the most expensive, not to mention possibly dangerous, cause to your furnace leaking water. This can occur for a variety of reasons but the most common one is simply age. However, when the heat exchanger is cracked, it usually flips the safety switch inside your furnace, which shuts it down completely. Cracked heat exchangers are a serious issue, which needs immediate repair by a HVAC professional.


HVAC systems with built-in humidifiers are connected to the plumbing inside your home. When the humidifier is clogged, it can cause water to leak, making you think it’s coming from your furnace. The water is actually coming from the plumbing, which resolves as soon as the clog is cleared. If there is a crack in the humidifier, it will need to be replaced. An HVAC professional is able to quickly identify the issue and let you know what needs to be done.

If you find water around your furnace, don't panic. At Harwich Port Heating and Cooling, we'll quickly diagnose the issue and help you find a solution. For more information about furnace leaks or other HVAC issues, contact us at (508) 593-9436.

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