Furnace Water Leak and Potential Causes

It is common knowledge that if you see water on the floor near your furnace that this is a sign of something being wrong.  It could be a sign of a large problem however, more often than not, it’s a minor problem and fairly straight forward to fix.

In the cooling mode, the indoor evaporator coil and it’s suction line can sweat.  Your suction line should have insulation on it because it’s purpose is to keep any condensation from dripping on your floor.  If that insulation is missing or has open seams then you will see the condensation on the floor causing you to think that there is a furnace leak.  Luckily this is easy to fix!  All the insulation joints should be closed tight and well taped to help prevent this condensation from dripping and causing problems.

In the summer months, for those lucky enough to have central air conditioning, you may see the evaporator portion of your indoor unit produce a lot of condensation.  This condensation should run down the coil into a pan and then out to the drain.  This drain can go into the ground, outside the house or into a condensate pump.  If it goes into the condensate pump then the pump will take the water outside the house or into a drain for you.  If the coil is dirty the water will hit the dirt and drip onto the floor instead of run down the coil.  This is one of the many reasons that your coils should be cleaned annually at minimum.

If the coil is dirty then the water will mix with the dirt and the dirt then can be deposited into the drip pan, drain, drain trap and anywhere else the water moves, causing problems.  The bottom of the drain trap is the most common area to see a clog.  The good news is that it can be cleaned out with a long flexible cleaning brush and flushing water down the cleanout cap.  It is important to mention that it does not take much dirt to clog your drain.  No matter if your unit is in the attic or the basement, this can cause some pretty terrible damage in your home.  This is why we always encourage utilizing our monthly service contract to ensure that your air filter is being changed and that your are keeping up with your annual inspections to keep your unit running efficiently.

We would like to note that occasionally the indoor coil can ice up.  And as you would suspect, when the ice melts, water will drip onto the floor.  You should never see ice anywhere on your system and if you do then you need to call a professional as this can be a sign of a bigger issue.

Now, these issues are not specific to summer time only.  If you have a high efficiency furnace you may have noticed that it produces condensate already.  With that the also have systems in place to drain this condensate.  There are many parts in the furnace that can leak, drip or crack and cause water to leak.  If you have a high efficiency unit you most likely have a central humidifier and this can also be a source of leaks as well.  Your furnace and humidifier needs to be cleaned and serviced annually.