When you think of furnaces, you generally do not think of furnaces as leaking. However, furnaces can leak. There are a number of different kinds of furnaces, each with its own kind of leak. The following will attempt to address what is causing each kind of leak, and how to fix it.

The Oil Furnace Leak 

Yikes. This is probably one of the most dangerous kinds of leaks because your furnace is leaking valuable fuel that can easily ignite. If the oil is leaking close to the part where the oil is ignited to produce heat, you should shut off the fuel supply line right away. This is an exceedingly dangerous leak area. Additionally, since the oil pump will continue to push/pull the oil through the line as pressure decreases from the leak, you will have an even bigger leak and repair problem before too long. An HVAC contractor will replace the parts that are leaking and restore your heat within an hour or less.

The Boiler Leak

The boiler leak is usually water, which is good news. It is not nearly as dangerous, but since your boiler needs water and steam pressure to create heat, it means you will get less and less heat as the boiler continues to leak. Usually, this means that the hose that brings water into the boiler is leaking, or that there is a valve leaking somewhere. It is a quick fix then, as it will not take the HVAC technician that much time to open up the front access panel on the boiler to find where the boiler is leaking from. 

Gas Heating Leak (Water)

Gas furnaces tend to leak gas. However, sometimes they "leak" water. If you see water dripping from a gas furnace, it is usually condensation. The condensation indicates that there is moisture inside the furnace and that the heat produced by burning the gas is causing the moisture to turn into condensation. This is probably one of the easiest things to fix because you can just open the access panel, wipe everything dry (as much as you possibly can without igniting the toweling or rag), and place the access panel back on the furnace. If it continues to leak "water," then call an HVAC technician. The heating repairs involved here may be a little more complicated than just wiping moisture off of and out of the surface areas of the furnace.