Furnace Leaking Water in Winter: What To Do

Illinois winters require a furnace that works effectively and efficiently. Discovering that your furnace is leaking water in the winter when the temperatures outside begin to plummet is stressful. How serious is the leak? Will you need to replace your furnace? JC Heating & Cooling, Burr Ridge’s choice for furnace repair service, has answers to these questions and more. We understand how important it is to have a reliable furnace to keep your home and family warm during frigid weather. Our technicians have the knowledge and expertise to diagnose and repair your furnace leak with less effort and cost than you might expect. 

Even if everything in your home is running smoothly, you should know what type of heating system and furnace you have. When you are familiar with your heating system’s age and technical specifications, it is much easier to troubleshoot the issue before small problems turn into bigger ones.

Types of Central Home Heating Systems

First, let’s talk about what kind of central heating system your home has. Put simply, the heating system is the conduit for the heat the furnace produces. The most common types are forced air and draft systems.

Forced Air Systems

Unless you live in an older home, your heat likely runs on a forced air system. Forced air systems have four main components: controls, an air handler, a heat exchanger, and a fan (or blower). 

When your home needs heating, the furnace turns on and activates the heat exchanger. The cold air in your home is pulled into the heat exchanger through the air return ducts and is warmed as it passes through the exchanger. The blower then forces the warm air through the duct system and back into the house. 

Natural Draft Systems

Older homes typically relied on natural draft furnaces for heat. While rarely found in new homes because of their low efficiency rating, they are still in use.  

A natural draft system does not use a fan to circulate warm air through the home. Instead, it relies on differences in atmospheric pressure inside and outside the furnace to propel warm air through the ducts. Natural draft systems also depend on the principle that hot air rises. Thus, while the cooler air flows into the furnace, the warm air rises through the ventilation system, creating a “natural draft” to heat your home.

Other systems that improve the efficiency of natural draft systems include forced draft, balanced draft, and induced draft systems. 

Types of Furnaces

Different furnaces use different technologies to operate, but for the most part, they fall into two categories: conventional and condensing.  

Conventional Furnaces

All furnaces produce exhaust gases when they are running. In a conventional furnace, a metal exhaust pipe vents the gases outside through a flue. 

Condensing Furnaces

Condensing furnaces also produce exhaust gas while in use but utilize primary and secondary exchangers to increase efficiency. Instead of venting the exhaust gases to the outside, condensing furnaces extract more heat from the gas. As the gases cool down after heat extraction, they condense into water and flow out of the furnace through a PVC pipe. 

While other furnaces are available, a general understanding of the most common systems will help you troubleshoot a furnace leak. At JC Heating & Cooling, our experts are highly trained and knowledgeable in all types of furnaces and heating systems. 

Five Reasons Your Furnace Is Leaking

Now that you have a basic understanding of your heating system and furnace, let’s address why your furnace is leaking. 

1. Deficient Vent Pipes

As with any piping in your home, a pipe fitted incorrectly is often the cause of your furnace leak. In the case of a conventional furnace, the gases from the furnace are not used and are immediately released. This means the gases do not have time to cool and condense in the pipe. However, insufficient flue or vent design or installation allows the exhaust gases to stay in the pipe long enough to condense. As a result, the water leaks back into your furnace.  

2. Humidifier Leaks

Many high-efficiency furnaces have built-in humidifiers in their air handlers, ensuring the air isn’t too dry and increasing performance by trapping more warm air. The humidifier is usually located outside your furnace and has mechanisms to control humidity levels. The most common reason for a leak in the humidifier is a clogged filter, which is easy to fix by changing the filter. If your humidifier is leaking, it could be dripping water into your furnace and causing serious damage.   

3. Condensate Pump

If you have a condensing furnace, the leak may result from a malfunctioning condensate pump. Condensate pumps force the condensation created by exhaust gases out to the vent pipe. If the pump is not working properly, the water backs up and causes a leak. 

4. Secondary Heat Exchanger

The secondary heat exchanger in your condensing furnace absorbs exhaust gases from the primary heat exchanger and cycles them into more heat, creating water vapor. If your secondary heat exchanger is damaged, it often means that your furnace is close to the end of its life. Secondary heat exchangers are expensive to repair, so it may be more cost-effective to replace the furnace. 

5. AC Issues

If your furnace connects in any way to your AC unit, the problem may not be with the furnace at all. While furnaces have humidifiers, AC systems have dehumidifiers to absorb the moisture from the air in your home, draining it through a condensate line. If your condensate drain line is leaking or clogged, water from the line may leak into your furnace, making it look like it is leaking. 

Is your furnace leaking water in the winter? Let the professionals at JC Heating & Cooling set your mind at ease. Our highly trained team will diagnose your furnace problems and let you know when they are fixable or when it’s time to let go of your old furnace. Call us today at (708) 968-3131 to schedule an appointment.