Why is My Furnace Leaking Water?

Furnace leaking water in Anchorage, AK.

You just discovered there’s a puddle water on the floor in front of your furnace. What does this mean? Why would your furnace be leaking water? In most cases, it’s not a big repair, so don’t panic. It could be a few different things. However, you will need a certified professional to take a look at it and resolve the issue for you. Don’t delay. Any issue dealing with water can quickly get complicated, not to mention moldy, if not addressed in a timely manner. Call Alkota Plumbing and Heating to speak to one of our certified technicians or to schedule one of them to come out to your Anchorage, AK, home today.

Type of Furnace

There are a few different reasons your furnace could be leaking water, but the most common reason is a condensation leak. But before a causal determination can be made, the service professional needs to know what type of furnace you have. Is it a high-efficiency (condensing) or standard-efficiency (conventional) furnace? If you don’t know right off the bat, it’s easy to tell. Take a look at its vent or exhaust pipe. If the pipe is white plastic (PVC), then your furnace is a high efficiency.

Another way to tell if it’s high efficiency is by its AFUE (Annual Fuel Utilization Efficiency) rating. If it’s rated 90 percent or higher, it has a cool exhaust and produces condensation, therefore, it’s a high efficiency. On the other hand, if your furnace has a metal exhaust pipe, it’s a standard-efficiency furnace and shouldn’t have condensation. It will have an AFUE below 90 percent. Many times furnaces have their AFUE rating printed on a yellow energy guide sticker on the unit. But that’s not always the case, especially in older models. Taking a look at the vent or exhaust pipe is a pretty foolproof technique, so don’t worry if you don’t know your furnace’s AFUE rating.

Possible Causes of Leak

Again, the most common reason for a leaking furnace is a condensation leak. High-efficiency furnaces extract heat from the combustion gases for a longer period of time than a standard-efficiency furnace does, causing the gases to cool, then condense. The condensation is routed to a floor drain. If the cause of the leaking water is condensation, there are a few possibilities. You might have a clogged condensation drain or tubing, a break in the condensation line, or issues with the condensate pump, if you have one. A standard-efficiency furnace extracts some heat from the combustion gases and quickly vents them out the exhaust or flue pipe. If you have a condensation leak with a standard efficiency, then its exhaust or flue pipe may be incorrectly sized. There should be no water involved with a standard-efficiency furnace.

You need to call in a professional to assess what’s going on. If he or she rules out a condensation leak, there are other possibilities, all still requiring a professional. One option may be an issue with your whole-house humidifier, if you have one connected to the furnace. It could be leaking inside your furnace, though having an annual maintenance appointment on your HVAC system should prevent this from happening. Another possibility is an internal drain system clog. If your air conditioning is running, and it shares an internal drain with your furnace, your drain could have an obstruction causing the water to be sent to your furnace. The most expensive option could be a faulty furnace secondary heat exchanger, but this possibility is only an option for the high-efficiency furnaces. This cause translates to you needing to replace your furnace.

Contact Us

Whatever the reason may be for your furnace leak, it’s time to call in a professional. Our Alkota Plumbing and Heating certified technicians can be reached at 907-332-5325 and are happy to assist you.