Why is my Furnace Leaking Water?

Why is my Furnace Leaking Water? J&A South Park of Pittsburgh, PA fix leaking water heaters.

Can water leaking from your furnace be a major problem?

As a certified Trane dealer, we want to make sure your furnace is running smoothly!

In a picture-perfect world, there’s no way we’d have to deal with unwanted surprises with our home appliances, but unfortunately, that’s not the case. From time to time, troubles are waiting for you when you first walk in the door.

Leaks are a rather common problem for furnaces, and there are various explanations for why they happen. Some major, others minor.

If you arrive home to a furnace leaking water, you’re most apt to call a technician to come out and identify the problem. But it certainly doesn’t hurt to stay well-informed on the assorted components of your home.

To give you a helping hand, we’re going to go over the chief causes for water leaks in your furnace. Then, where applicable, we’ll look at the next steps to take.

But first, if you’re not already aware, you need to determine what type of furnace you have, high efficiency or conventional standard-efficiency.

What if it’s a high-efficiency furnace?

Many furnaces leak water due to a malfunctioning condensation drain or tube. This type of leak can occur with a high-efficiency furnace, which extracts heat from combustion gases over a longer period than a conventional unit.

High-efficiency furnaces create water because they have two heat exchangers, one more than a conventional furnace.

The two heat exchangers absorb so much heat that the exhaust gas changes from a gas state to a liquid state. Condensation forms and then drains out through the condensate line.

Your high-efficiency furnace must be properly serviced so it can adequately drain the water that condensates. If there’s any leak or clog, the condensation can’t be carried out of your home and ends up pooling around the furnace.

How can I tell if I have a high-efficiency furnace?

If you’re not sure what type of furnace you have, it’s easy to identify it yourself. Take a look at the furnace vent or exhaust pipe. If the pipe is a white plastic (PVC), then your furnace is a high-efficiency system.

Another way of identifying it is by the annual fuel utilization efficiency (AFUE) rating. If the rating is 90 percent or more, your furnace has a cool exhaust and generates condensation; therefore, it’s defined as high efficiency.

Alternatively, if your unit has a metal exhaust pipe, it’s a standard-efficiency furnace and shouldn’t retain any condensation. It will have an AFUE below 90 percent.

Oft times, furnaces have their AFUE rating printed on a yellow energy guide sticker in plain sight on the unit, given that the Federal Trade Commission has very strict consumer product rules for making known the system’s energy usage.

What about a DIY fix?

If your high-efficiency unit is leaking, you’ll want to check the drain trap to see if it’s clogged. The drain trap collects dirt and water over time. If it’s clogged, you can use a shop vac to clear it.
But if the condensate pump, humidifier, or drain line is broken, you’ll need to schedule a repair with your technician.

If you’re not sure about the cause, one of our expert HVAC technicians at J&A South Park can diagnose your furnace for you.

A high efficiency furnace system can help avoid furnace leaks and can be fixed by J&A South Park of Pittsburgh, PA.

What to do when you first notice a leak with your standard-efficiency furnace?

When you do spot water dripping from your furnace or pooling at the base, you need to act swiftly. There should be no water involved with a standard-efficiency furnace.
Before a technician comes to your home to identify the exact cause, it’s essential that you do a few things.

First things first. If you notice your furnace leaking water, you’re going to want to turn off your furnace. You should see a switch on or next to the furnace. If you can’t locate it, turn the system off at the breaker.

You’ll need to clean up the water that has pooled around the base. It’s critical to thoroughly soak up all water since water damage happens without delay. If you have excessive amounts of water, you might want to rent a wet-dry vacuum.

If you can discover where the leak is originating from, this should be a good idea of the problem. However, you’re still going to need professional assistance. A qualified technician will be able to quickly diagnose a furnace leaking water and let you know exactly what needs to be done.

Keep in mind, your homeowner’s insurance isn’t likely to cover water damage due to a lack of maintenance. If you reach the puddle, mop it up and place a shallow tray underneath the furnace to catch the drips.

Bottom line: Don’t delay. Any issue dealing with water can get complicated swiftly if not tackled in a timely manner. It can also quickly snowball into impacting other areas of your home, such as mildew, leading to poor indoor air quality.

If your standard-efficiency furnace is leaking water, it’s most likely due to one of these reasons described below.

Clogged furnace filter causing furnace leaks and can be fixed by J&A South Park of Pittsburgh, PA.

A clogged filter

Ah, the ubiquitous furnace filter! The first place you’ll want to inspect is your furnace’s air filter. If your filter is dirty and clogged, it will limit airflow through the furnace coil. Many times, this causes the coil to freeze. However, every so often, it can cause water to leak and pool around the furnace.

As we’ve mentioned in most blogs about furnace upkeep, make sure you always check your furnace’s air filter condition and replace it with a new filter if it’s dirty.

Poorly designed exhaust pipe

As described above, if your furnace includes an AFUE rating of less than 90, it’ll have a metal exhaust vent pipe (versus the white PVC vent pipe on a high-efficiency furnace).

This exhaust vent carries away the gases created during the combustion process and discharges them to the outside while they’re still hot.

But if the exhaust pipe is either too large or doesn’t slope upwards enough, it slows down the movement of the gas as it travels outside. This allows the gasses to cool down and condense into water while still in the exhaust pipe, causing leakage.

You can begin by inspecting the pipe by assessing its shape, structure, and integrity. If something about the pipe itself seems wrong, you should consult a professional for further advice concerning any changes to the vent pipe’s design and installation. The scope of this project is beyond what most typical homeowners have the tools and expertise to carry out.

If it’s not the vent pipe that’s the issue, you’ll next want to check the furnace’s built-in humidifier. This is usually visible on the exterior of the furnace.

Furnace humidifier problem

Another culprit may be your home humidifier if you have one attached to your HVAC system.

Many homeowners choose to add a humidifier to their heating systems to make their homes more comfortable during the dry winter months. Such humidifiers are designed to ensure that the air circulating back into the house from the furnace isn’t too dry. Consequently, humidifiers use water to add moisture to the air. There’s typically an elaborate mechanism that delivers water into a humidifier that’s outside of the furnace.

Point is, furnace leaks are frequently linked to these humidifiers. The leaking humidifier evidently has a loose pipe or some other problem causing surplus water to build up and spillover.

If the pipe is blocked, your humidifier could possibly be adding dirty moisture to the air, so this is one issue to get fixed promptly. If, however, there is a crack in the humidifier, it will most likely need to be replaced.

For leaks caused by the humidifier, your HVAC technician will first check the water lines for any cracks or pinhole leaks. He/she will also check the connections between your humidifier and water lines for proper fit. Ill-fitting and poorly connected lines can easily result in unexpected water leaks.

A malfunctioning heat exchanger

A malfunctioning heat exchanger inside your HVAC system is one of the most expensive, not to mention dangerous, reasons for your furnace leaking water.

All heat exchangers fail sooner or later. This is due to metal fatigue. Metal, when heated, expands, and when it cools, it contracts. This expansion/contraction sequence is a function of the normal healing process. Over time, this constant expansion/contraction has the same consequence on a heat exchanger as bending a paperclip back and forth: it breaks. And when that occurs, contamination follows, and it’s no longer safe.

While heat exchangers last between 10 and 20 years on average, a number of factors can hasten failure. These factors usually include poor maintenance, poor initial system design, and installation, or poor equipment design by the manufacturer. Anyone or a combination of these is capable of bringing about a heat exchanger breakdown in just a few years.

So, how do you know when a heat exchanger has failed?

A heat exchanger must be visually examined on a regular basis. Visual inspection of light or water passing through the breach is positive proof of a crack or hole in the unit.

The long-standing technique of a mirror and a flashlight has been swapped with a high-tech infrared video inspection system wherein the technician can look into unrealistic places using only a mirror.

What are my options?

Heat exchanger repairs can be complicated and time-consuming. Most technicians find it easier and safer to replace the heat exchanger itself or even the entire furnace. If the unit is under warranty, the first option is a good way to proceed unless it’s unavailable in the time frame needed, which can be immediate in cold weather.

If the furnace is out of warranty, the preferable option would be to replace the entire furnace.

Air conditioner system causing furnace leaks and can be fixed by J&A South Park of Pittsburgh, PA.

Is it an air conditioner problem?

What you might fear is a leaky furnace might not actually be the furnace after all. Instead, you might have an issue with you’re A/C unit. This is more probable if the furnace is part of your HVAC system or is directly or indirectly linked to an indoor A/C unit.

One of the chief functions of your air conditioner is to dehumidifier the ambient air in your home. This process consists of absorbing moisture from the air. Once it’s absorbed, the moisture drains out of your unit via a condensate drain line.

A clogged or leaky condensate drain line can cause water to leak into surrounding structures, including your furnace. This makes it seem like your furnace is leaking water, but it’s actually the A/C.

Final thoughts

The best way to avoid issues with your furnace is to keep it maintained and be on the look-out for all operational matters. It’s a good idea to have your furnace inspected and tuned-up each year. This increases the system’s longevity and helps keep your energy bills under control.

However, problems are always possible, and a furnace leaking water should never be ignored. While you most likely have a relatively minor issue, a leaky furnace could be the sign of a larger underlying problem.

Putting off a HVAC service call could cause significant damage to your entire system, leading to costly repairs, something any homeowner would like to avoid.

J&A South Park has been helping homeowners with heating and cooling issues for years. Just give us a call!

Our experienced technicians can help resolve any minor problems before they become a big headache. With J&A South Park’s help, you’ll rest easy knowing your home will stay comfortable, year-’round, without your having to lift a finger.

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