Since furnaces are primarily used for heating air, most homeowners associate them with a drying effect rather than humidity. However, furnaces can suddenly start leaking or dripping liquid water during the summer or winter. Regardless of the season or the cause, water leaking out of a furnace is a sign your heating system needs serious maintenance. A service technician is likely to discover at least one of the three following problems while investigating moisture coming from the inside of your furnace.
Condensation Drain Issues
Even though furnaces generally dry out the air they heat, some condensation is generated when raising the temperature of the home's air. This condensation is supposed to gather in a central pan and drain through the floor out into a buried pipe or similar exit. When this condensation pipe clogs up or the drain lines become broken, water redirects through or under the furnace and out around the appliance.
You can attempt to clean out the drain yourself, but this work is best left to a service professional since you must shut the furnace off before doing any work on it. If you stick to an annual or bi-annual maintenance schedule, you shouldn't have to deal with condensate drain clogs since checking and cleaning out this section is part of a standard package.
Heat Exchanger Problems
If there's no clog in the condensate drain but the puddles keep forming around your furnace, you may have a problem with your heat exchanger. High efficiency furnaces installed within the last few years may include a secondary heat exchanger to extract as much heat as possible from the waste gases. If this exchanger becomes cracked or clogged, condensation begins to drip off of the surface due to inefficient heat conversion. This problem usually requires the replacement of the entire furnace, so rule it out first with an inspection from a furnace professional.
Gas and oil furnaces require venting through the wall or ceiling of the home to carry away dangerous fumes and gases. These vents are usually covered with small caps to keep water out, but these caps can easily fall off after years of use. Water dripping in through the vent can pour through the furnace and pool around the bottom of the equipment. Open vents don't just create a shock hazard by letting water in, they are also more prone to clogging up due to leaves or insect nests and forcing combustion fumes back into the rest of the home.
Talk to local furnace repair services for more help.