It can be frightening to see water pooling up on the floor next to your furnace. This situation can often make people think the worst and worry that they may have to have their furnace replaced. Luckily, this issue is usually fairly minor and is easy to repair. Nonetheless, you obviously want to have the issue taken care of quickly to ensure that the leak doesn’t lead to water damage or allow mold to start growing. The good news is that this problem is something you may be able to troubleshoot on your own, depending on what type of furnace you have.

Conventional Versus High-Efficiency Condensing Furnaces

Conventional furnaces shouldn’t really ever have issues with leaking as they don’t produce any water. If your home has a conventional, standard-efficiency furnace and you notice water near the unit, you need to immediately shut your heating system off until you can have a certified HVAC technician inspect it.

The only real reason a conventional furnace could have water around it is if the flue or exhaust vent isn’t working as it should. This creates a serious health risk since it can trap carbon monoxide inside your home. You should not run your heating system until you can have the flue inspected and repaired.

As your furnace burns gas to create heat, carbon monoxide and other dangerous combustion fumes are produced. When working correctly, these hot gases are drawn into the flue and vented out of the building. However, if the flue isn’t venting properly, the hot gases may be trapped inside the pipe. As the gases cool, condensation can form and drip out of the pipe onto the furnace or ground. This issue can potentially be deadly since it means that the carbon monoxide is not venting out of the house.

High-efficiency furnaces, on the other hand, can definitely be prone to leaking as they always produce condensation. This type of furnace is a two-stage heating system that uses a second heat exchanger, whereas conventional furnaces only have a single heat exchanger.

The initial process for creating heat is the same for both types of furnaces. The unit first ignites the combustion gas (usually natural gas or propane). As the gas burns, it transfers energy to a heat exchanger. The blower fan draws air in and forces it over the heat exchanger, raising the air’s temperature. The issue is that the heat exchanger is only able to utilize 80% to 90% of the heat energy created by burning the gas, and the rest of the heat travels out through the flue along with the combustion fumes.

In a high-efficiency furnace, the hot gases are transferred to a secondary heat exchanger instead of being immediately vented out through the flue. This second heat exchanger absorbs the majority of the remaining heat energy, which further cools the gases before they are vented. As the gases cool, it causes condensation to collect inside the furnace. This process produces water that travels through the same condensate drain system used by your AC system. If the condensate drain system isn’t working, water will collect inside it and eventually begin to leak out.

Condensate Drain System Issues

If you have a high-efficiency furnace that is leaking, it means that there is an issue with the condensate drain system. The most common reason this occurs is that the condensate drain pipe is clogged. Mold and mildew often collect inside the drain lines due to the heat from your furnace. Dirt and debris can also get into the system and cause it to become clogged. If the pipe is clogged, water will start to back up and eventually overflow out of the condensate drain pan.

When looking at your furnace, you should see a series of small white PVC pipes coming out of the furnace and the air handler. The pipe coming out of the air handler is the drain system for your AC. Depending on how the drain system is set up, the two pipes may join together. If your furnace and HVAC system is in the basement, these pipes likely run to a nearby floor drain. With this type of setup, you should first make sure that the floor drain isn’t clogged as this will cause the water to back up.

If the floor drain is working, then the odds are the drain line is clogged. You may be able to unclog the drain line on your own using a wet/dry vacuum. However, this usually only works for minor clogs, which is why you may need to have an HVAC technician clear the line for you.

If your HVAC system is on the ground floor or there isn’t a floor drain near the system, it most likely uses a condensate pump that forces the water through a pipe that drains outside the home. With this setup, it could be that either the drain line is clogged or that the condensate pump is broken and needs replacement or repair.

Leaks can also occur if any of the drain lines are broken or damaged. In this situation, a technician will need to replace the pipe to prevent it from leaking.

Another possible cause of this problem is that your condensate drain pan has rusted out or been damaged. Metal drain pans can sometimes be prone to corrosion due to water constantly sitting inside. Over time, rust can eat through the pan and cause it to develop holes. Some HVAC systems have plastic drain pans; over time, these may become brittle, crack and start leaking. Drain pan issues could potentially be more serious as replacing the pan is not always possible. In this case, you would need to replace the entire unit.

Furnace Versus AC Issues

If you see water pooling or leaking when your furnace is on, this issue is obviously related to your heating system. However, your air conditioning can also cause water to pool up around your furnace since the AC air handler is often located directly next to the furnace. Again, this is usually related to some issue with the condensate drain system.

However, it can also occur as a result of the AC evaporator coil freezing. When the coil thaws, it often produces more water than the drain system can handle at one time. As a result, the drain pan will overflow, and water will start leaking out of the air handler onto the floor.

Reliable Furnace and AC Services

If your furnace is leaking, the highly trained technicians at Healthy Home Heating & Cooling LLC can inspect your flue and condensate drain system to determine why. We repair and service all furnace and AC models from any manufacturer, and we are available 24/7 for any emergency situations. Our team also specializes in cooling and heating installation for residents of De Pere and the surrounding areas, including conventional and high-efficiency furnaces, central air conditioners, heat pumps, boilers and ductless mini-splits. We have been in business for nearly two decades, and our team has more than 30 years of experience. To schedule an appointment to have your leaking furnace inspected, give us a call today.

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