Skip to content

Why Is My Furnace Leaking Water?

Caucasian repairman or blue collar/service industry worker makes service/house call at customer's front door. He holds his clipboard and tool box filled with work tools. Inspector, exterminator, electrician. He wears a navy blue uniform. Service truck seen in background parked on road.

You’ve just discovered there is a puddle of 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 no need to panic. The presence of a water puddle can point to a few different problems that will require the expertise of a certified professional to resolve the issue for you. Don’t delay – water leakage can quickly get complicated (mold, damage to flooring) if not addressed timely. Call Arise today to speak to one of our certified technicians or to schedule an appointment to your Cedar Park, TX, home.

Type of Furnace

There are a few different reasons your furnace could be leaking water. The most common issue is a condensation leak. 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, here is an easy way to tell: take a look at its vent (or exhaust) pipe. If the pipe is white plastic (PVC), then your furnace is 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 that will produce condensation. On the other hand, if your furnace has a metal exhaust pipe, it’s a standard-efficiency furnace and should not produce condensation. A standard efficiency furnace will have an AFUE below 90 percent (usually 70% to 85%). Many times a furnace will have a yellow energy guide sticker on the unit that shows the AFUE rating (except in extremely old furnaces). 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 Water Leak

As stated above, 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 and then condense. The condensation is routed to a drain line. If the cause of the leaking water is condensation, 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.

With any water issue, it’s always best to depend on a professional assessment. Once a condensation leak is ruled out, the issue could point to a whole-house humidifier leaking through the furnace. Having routine preventive maintenance performed regularly 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 overflow through your furnace.

The most expensive option could be a faulty furnace secondary heat exchanger on a high-efficiency furnace. This issue would require replacement of the entire furnace.

Whatever the reason for your furnace leak, it’s a good idea to call in a professional furnace technician. Our trained and certified technicians can be reached at 512-267-5000 and are always happy to assist you.

Need HVAC Service?

Contact Arise Services today!

Call us at 512-267-5000!

Read More of Our Articles

View other articles.
Arise Services blue logo.