Why Is My Furnace Leaking Water?

You just discovered there is a puddle of water on the floor in front of your furnace. Why would the furnace in your Chandler home be leaking?

It could be a few different things. In most cases, it is not a big repair, so keep calm.

However, you will need one of our Mason Pro Services heating, ventilation, and air conditioning (HVAC) professionals to take a good look at it and resolve the issue for you.

No One Wants to Be in Deep Water

Do not delay. Any issue dealing with water can quickly get complicated if not addressed in a timely manner. It can also speedily snowball into other problems, such as mold and poor indoor air quality, in your Arizona home.

Schedule one of our highly trained professionals to diagnose the furnace problem as soon as possible.

How to Identify Your Furnace Type

The fastest way to tell is to look at the vent or exhaust pipe on your furnace: white PVC plastic means a high-efficiency (condensing) furnace, while metal means a standard-efficiency (conventional) furnace.

Before our HVAC expert can pin down the cause, they need to know which type you have. Another way to check is the annual fuel utilization efficiency (AFUE) rating: for Chandler and the rest of Arizona, the high-efficiency tier starts at 90% AFUE, since Arizona falls under ENERGY STAR’s “U.S. South” region requirement for gas furnaces. That higher rating is also why these furnaces produce condensation in the first place. They pull heat out of the combustion gases for longer than a standard furnace does, which cools the gases enough that they condense.

If your furnace has a metal exhaust pipe instead, it is a standard-efficiency furnace with an AFUE rating below 90 percent, and it should not be producing any condensation at all.

Many furnaces have their AFUE rating printed on a yellow energy guide sticker right on the unit, and manufacturers are required to disclose that number there under the FTC’s EnergyGuide labeling rules. Older units do not always have a legible sticker, but the exhaust-pipe check above is accurate enough, so do not worry if you cannot find yours.

The Possible Causes of a Furnace Water Leak

The most common cause by far is a condensation leak, but there are a few other possibilities our technicians rule in or out once they’re on-site.

Is It a Condensation Leak?

Yes, most likely. If you have a high-efficiency furnace, a condensation leak is the top suspect. The condensate is supposed to route to a drain, so look for a clogged condensation line, a break in the tubing, or a failed condensate pump.

A standard-efficiency furnace, on the other hand, vents combustion gases out hot and should produce no condensation at all. If yours is leaking anyway, the exhaust or flue pipe may simply be the wrong size for the unit.

Could It Be Your Whole-House Humidifier?

It’s possible, especially if your humidifier is plumbed directly into the furnace. A unit that’s leaking internally can send water into the furnace cabinet, which is one more reason annual preventative maintenance pays for itself.

Is an Internal Drain Clog to Blame?

If your air conditioner shares an internal drain with your furnace, yes. A clog in that line can back water up into the furnace, especially when your AC is running hard during a Chandler summer.

Could It Be a Failing Secondary Heat Exchanger?

In rare cases, yes. A faulty secondary heat exchanger only affects high-efficiency furnaces, and it’s the worst-case scenario on this list.

Just so you are aware, this issue generally results in a full furnace replacement rather than a repair. It’s rare, but it’s exactly why we always recommend a professional diagnosis instead of guessing.

Either way, you really need one of our HVAC professionals to assess what’s going on in your Chandler home. Once we rule out a condensation leak, we can help you run down the rest of the list.

Call the Furnace Experts in Chandler!

Whatever the reason for your furnace leak, it is time to call a professional. At Mason Pro Services, we are always happy to assist you in every aspect of furnace care for homes throughout Chandler, from Ocotillo to the Price Corridor. Call us at 602-680-5086 or request service online.