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A nice puddle to jump in after a rain shower leaves you with a fun, happy feeling. Finding a puddle of water that has leaked from your furnace – not so much. A furnace leaking water doesn’t usually mean a huge repair bill, so don’t worry just yet!

You will need an HVAC service professional to visually inspect and test the unit in order to diagnose this with certainty, but here is some information to give you a little insight into if you may have this type of leak. High-efficiency furnaces (95%+ AFUE) will be more likely to leak water due to condensation because they extract heat from the combustion gases for a longer period of time when compared to standard-efficiency furnaces. Standard efficiency furnaces (80% AFUE) vent this water out an exhaust or flue pipe. In high-efficiency systems, however, this condensation is routed to a floor drain. Here is where a few issues may arise.

If you do have a furnace leaking water, here are the main culprits:

During AC season:

  1. A clogged drain line causing backup into the drain pain

  2. A dirty filter/low refrigerant has caused freezing inside the unit that is thawing

During furnace season:

  1. Issues with the condensate pump

  2. High efficiency furnace drain line is clogged due to excess condensation

  3. Seals behind the inducer motor have failed (you may see rust spots on the unit)

If you have a standard efficiency system it is still possible that you just have a condensation leak but would most likely be due to the exhaust or flue pipe being incorrectly sized.

If your HVAC service expert determines that you do not have a condensation leak, there are a myriad of other issues that could be the cause of your furnace leaking water. They include

  1. Issues with your whole-house humidifier (if you have one)
  2. Internal drain clog
  3. Bad secondary heat exchanger in the furnace – the most expensive to repair and may need replaced entirely
  4. Air conditioner leaking

Air conditioner leaking, you say? Yes, in seasons where you may use the furnace and air conditioner it is possible that when you are using the AC your condensation pan can fill with water and drip into your heating system, making you think you have a furnace leak problem.


First, call a professional HVAC service company. You’ll want to tell them about your issue and get on the schedule as quickly as possible.

Then, make sure you shut your system off. There should be a switch next to the furnace. If you cannot locate this switch, then turn the system off at the breaker box.

Clean up all the water as best as you can. Water damage can happen quickly and this will also allow the technician to get access to the unit more quickly when he or she arrives.


In short, yes. If your furnace has water on the floor around it, you want to be sure you call for furnace repair. Left without repair, the water can drip onto your circuit board, get into the blower motor and eventually cause the furnace to shut down.


Call us at Quality Comfort Home Services at 513-216-0586 if you are experiencing a furnace leak or are in need of any other furnace repair. You can also book online at our website Our trained and certified technicians come with fully stocked vehicles, ready to fix your furnace problem. We also provide a lifetime guarantee on our repairs.