Common Causes and Solutions
A furnace leaking water is a common problem for homeowners. If left unchecked, it could lead to high repair costs and damage to your property that can cause severe risk to your health. If the leak continues, your furnace will eventually fail and need to be replaced. It's always best to deal with a water leak early before it becomes a bigger problem.
There are several possible reasons behind your furnace leaking water, a few you may be able to address yourself and others that will require a technician to fix the problem. To understand why your furnace is leaking water, you need to know the type of unit you have in your home to figure out the possible causes of your leaking furnace.
High Efficiency vs. Conventional
A high-efficiency condensing furnace and a conventional furnace have many commonalities. To help determine the type of furnace in your home, there are three differences. If the material on your furnace exhaust pipe is PVC (polyvinyl chloride), you more than likely have a high-efficiency furnace. A metal pipe is usually found on a conventional standard furnace. Having an AFUE (Annual Fuel Utilization Efficiency) rating of 80% would suggest you have a conventional furnace; high-efficiency furnaces have a rating of 90% or above. The AFUE rating should be printed on a yellow EnergyGuide label on the unit. In addition, most newer homes have a high-efficiency furnace while older homes that have not been updated have a conventional furnace.
A conventional furnace, also known as a standard efficiency furnace, does not produce water. However, if you have a high-efficiency furnace, condensation will happen due to the addition of the second heat exchanger. This is why a high-efficiency furnace is also known as a condensing furnace, and a standard efficiency furnace is a non-condensing furnace.
High-efficiency furnaces possess a secondary heat exchanger to extract heat from the exhaust gasses, which is one reason they are more efficient. The cool exhaust gasses produce condensation. The moisture is directed into a drain line that empties into a floor drain. A water leakage occurs when the condensation is unable to drain properly.
What Causes a Furnace to Leak Water?
Now that you’ve determined which furnace you have, let’s look at why it could be leaking.
Condensation Leak
One of the most common causes of a furnace leaking water is water condensation. Clogged dirt and debris in the drain hose, drain line, or condensate trap cause water to leak. The line may have simply disconnected but broken condensate pumps and cracked pipes must be replaced. A condensate pump typically lasts three to five years. If your pump is older, it may not perform optimally. The pump will cost about $50, and to have it professionally replaced can range between $100 to $200.
Solution: You can try flushing a clogged line with equal parts white vinegar and hot water. Repeat the process several times if needed. To avoid a clogged furnace condensate drain or line, have the furnace inspected and cleaned at least once a year. Condensation on a high-efficiency furnace is often normal, but it’s still a good idea to have a furnace specialist come take a look for any cracked pipes or other leak sources.
Malfunctioning Heat Exchange
Condensation leaks can result from a malfunctioning secondary heat exchanger. The primary heat exchanger extracts heat from the burning gas and is more prone to cracking since it is situated near the flames and receives more stress. The secondary heat exchanger extracts additional heat from the exhaust gasses, which would otherwise be wasted. The cooling gasses result in the formation of condensation. A faulty secondary heat exchanger might cause a condensation leak.
Solution: Heat exchanger issues are expensive, and the part will need to be replaced by an HVAC professional, which could cost around $1,500. In some cases, the entire furnace needs to be replaced
Clogged Air Filter / Blocked Air Return
If the filter is clogged, it disrupts the furnace’s temperature regulation and forces it to work harder to heat your home. As it works harder, it can lead to more condensation, as well as more expensive heating bills. A clogged filter restricts the airflow, which can cause the coils to become too cold and freeze. The ice melts and drips onto the floor beneath the furnace when the air conditioner shuts off. In addition, a blocked air return vent can cause the system to work less efficiently and produce more condensation. When the system is overworked due to a blocked air return, parts may also crack or break, leading to leaks.
Solution: Replace your clogged filter for a new one and change your filter about every three months.
Broken Humidifier or Ill-Fitted Exhaust Pipe
In a conventional furnace, the built-in humidifier empties excess water through the furnace drain line. If the drain line is clogged, the water will build up, leaking from the humidifier into the furnace. It will appear that water is leaking from furnace components when the humidifier is the challenged part.
Solution: Inspect the furnace humidifier water lines for cracks or pinhole leaks. Double-check the fit of the lines to the humidifier. Ill-fitted lines can easily create leaks. If the humidifier appears to work correctly, inspect the exhaust pipe. If the pipe is loose or improperly fitted to the furnace, water that’s meant to be expelled will leak from the unit. Be careful examining the pipe. A conventional furnace exhaust pipe can become dangerously hot; do not touch it. Call an HVAC professional to repair or replace the pipe and to prevent water damage and mold growth.
Leaking Air Conditioner Unit
If you have a conventional furnace, which doesn’t generate any water, standing water around your furnace is probably coming from another appliance. Air conditioning units contain condensate drain pans to collect moisture from the evaporator coils. A clogged pan can cause water to overflow onto the floor. If you have recently been running your air conditioner, a clogged drain pan might be the issue.
Solution: The drain pan needs to be drained and the clog removed. You can attempt to resolve this issue yourself or call an HVAC technician.
Plumbing Leak
The leaking water may not be coming from your furnace; it might be a plumbing leak. A plumbing pipe located near your furnace could be damaged or clogged. The good news is that minor plumbing issues are often cheaper than furnace issues.
Solution: Call a plumber or an HVAC technician to diagnose and fix the problem.
Steps to Take When Your Furnace is Leaking
If you notice water pooling around the furnace as well as visible water stains or wet spots, your furnace may have a leak. Unusual sounds or odors coming from the furnace could also be an indicator that something is not working properly. Because there is a risk of shock or electrocution when water is leaking from a furnace, it’s important not to try to fix the leaky furnace yourself, no matter what’s causing the leak. Instead, hire a furnace expert to safely handle the issue and get your home back to feeling normal. In the meantime, here are actions you can take to try to minimize the damage:
- Turn off the furnace and electricity to stop the water and protect yourself from electrical shocks. The furnace can be turned off at the thermostat, the switch on the furnace or the circuit breaker.
- Dry water that has pooled on the floor with towels, a mop or a wet-dry vacuum.
- Check the air filter and replace it if it’s dirty or wet.
- Check for a clogged condensate line. It can be flushed with equal parts white vinegar and hot water. Repeat the process several times if needed.
How to Prevent Your Furnace from Leaking Water
To prevent future water leaks in your furnace, there are a few preventive measures you can take.
Scheduling regular maintenance for your furnace is crucial. A professional technician can check for any potential issues and address them before they lead to water leaks.
Regularly change your furnace filter to trap dust, dirt, and other particles. Clogged filters can restrict airflow and make your system less efficient.
Regularly inspect and clean the condensate drain line to ensure it remains clear of debris. You can use a mixture of water and bleach to flush out any buildup.
Maintaining proper humidity levels in your home can also help prevent condensation and future water leaks. Consider using a dehumidifier if you live in a humid climate or if your home tends to retain moisture.
Make necessary repairs: make sure to replace the condensate pump if it starts to malfunction. Regularly inspect the pump and replace it if you notice any signs of damage or if it's not functioning properly.
Proper furnace installation requires specialized tools and installation expertise. Getting it right is the key to preventing future problems and expensive repairs. As it is one of the major household investments, it is vital to do your research in you choosing a reputable and knowledgeable company not only before buying a furnace, but also when installing it.
Professional HVAC installation and service providers evaluate your home’s size to determine the best heating options and offer customized heating solutions. Their EPA-trained and certified technicians help you choose the right furnace based on the size, type, energy efficiency and model to optimize your comfort. They will also inspect the existing ductwork and your current heating system to ensure there are no air leaks or damage.
Is a Leaking Furnace Dangerous?
Aside from the risk of shock or electrocution when water is leaking from a furnace, water damage can be destructive. Though it may not pose an immediate risk to your safety, it can impact your comfort and lead to costly outcomes if left untreated.
Rust can form on the furnace’s components, which decreases efficiency, leads to breakdowns and requires repairs. The heat exchanger is particularly vulnerable to rust, which can cause holes and cracks that can lead to exposure to harmful gases like carbon monoxide.
Water leaking inside the furnace can also damage the internal electrical components, causing the furnace to stop working altogether. Circuit control board is responsible for transmitting the signals needed to start the heating. If water leaks on to the circuit control board, it won’t be long before you need to replace it.
Dampness and moisture can cause mold growth, which can be harmful to your health and can cause respiratory issues. Water leakage can also cause damage to your flooring and furniture if not addressed in a timely manner. It can also cause damage to your electrical wiring, which can be potentially dangerous.
Don’t ignore the warning signs of a failing furnace. If you have persistent or recurring leaks, a lack of heating and cooling, or if you’re worried about your safety, it’s better to replace an aged unit while it’s still operable rather than wait until the winter months in the cold while you wait for an available company.
Contact a local Lennox Dealer today if you have questions about a leaking furnace or if you want more information about how to keep your home safe and healthy.
