High efficiency furnaces often develop exhaust pipe leaks. Why? Well, it’s actually normal for your high efficiency furnace to build up condensation. Usually, condensation drains via a pipe that leads to a floor drain where it safely exits your home. Sometimes, though, your pipe might develop clogs or there could be a crack somewhere along the tubing, leading to a condensation leak that makes a mess of your home. You’ll have to patch the leaking tubing in order to get rid of the exhaust pipe leak.
Standard efficiency furnaces do not have a dedicated condensation pipe, however, and should not be leaking water anywhere under normal operating conditions.
So why is your furnace exhaust pipe leaking water?
It could be that the exhaust pipe is the incorrect size. This could lead to the furnace exhaust cooling down within the pipe, condensing and becoming water vapor, causing a condensation leak.
Another explanation for a standard efficiency furnace exhaust pipe leaking water is that the joints in the pipe are vulnerable, allowing condensation to build up. Have a professional check your flue pipe and patch any holes.
Long-term exposure to water vapor can cause corrosion in your furnace exhaust pipe, so it’s important to fix any leaks ASAP.