A leaking furnace is more than a nuisance. It could be a sign that there is a more serious problem going on that requires professional service. If your furnace is leaking, here is what you need to know.  

What Type of Furnace Do You Have?

Before you can start to look into why your furnace is leaking, you have to find out what type of furnace you have. The furnace type goes beyond electric and gas. Furnaces are also divided into condensing and conventional types.  

To determine which furnace you have, look at the exhaust pipe that connects the furnace to your home. If the pipe is made of metal, it is likely a conventional furnace. However, if the pipe is made of PVC, it's a condensing furnace.  

What Causes a Condensing Furnace to Leak?

The most common cause of a condensing furnace leaking is the flue pipe was not installed correctly. The flue pipe helps to move hot exhaust from the furnace and out to vent. When the pipe is not the right size or incorrectly installed, the exhaust can build up in the pipe and cause leakage.  

The leakage could also be the result of a clog on the inside of the furnace. The furnace has a drain system that is supposed to collect the condensation and prevent it from leaking. However, the drain can occasionally clog.  

What Causes a Conventional Furnace to Leak?

A conventional furnace could be leaking water if there is an issue with the exhaust pipe. Ideally, the pipe will collect the fumes that come from the furnace and push them out. However, if the pipe is not installed correctly, the fumes can sometimes collect in the pipe and create water or condensation inside.  

The furnace could also leak if there is an issue with the humidifier. Not all furnaces have a humidifier attached, but for those that do, they should be affixed to the front of it. When the humidifier is clogged, water can appear to leak from the furnace. 

Your furnace's secondary heat exchanger could possibly be to blame, too. By nature, the secondary exchanger produces condensation, but it should not be to the point that it leaks. If it does, this could be a sign that the exchanger is faulty.  

The best way to determine the source of your leak is to have the furnace professional inspected. Schedule an inspection by a HVAC technician as soon as possible to prevent other problems from developing.