Why is My Furnace Leaking Water?

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Your furnace is an essential part of your home so it’s no surprise that when your furnace leaks water and needs repairs, it can quickly cause panic and stress. Not only will the leaking water affect the use of your furnace, but water leaks can cause serious issues within your home as well.

Any unusual furnace water leaks should be inspected and repaired by a professional furnace technician. At North Wind HVAC, we provide emergency furnace repair services 24 hours a day, seven days a week including weekends and holidays.

Possible Causes of a Leaking Furnace

There are several reasons why you could have a furnace water leak. Possible causes of water leaking from your furnace include:

Wood furnaces for heating a house

Condensation Leak

Today’s furnaces are designed to be more efficient than older furnace models. The Annual Fuel Utilization Efficiency (AFUE) is the standard measurement used to rate your furnace performance. High efficiency furnaces with an AFUE over 90 naturally produce furnace condensation when they heat your home. A built-in cool exhaust system removes the moisture through a PVC line that is attached to your basement floor drainage or through a wall to the outside of your home. If your condensation pump or PVC lines are damaged, blocked cracked, or faulty, the condensation cannot be removed from your appliance so you will see water leaking from your furnace.

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Humidifier Leak

Some home owners choose to have humidifiers installed in their furnace to improve the air quality within the home. The humidifier collects and dispenses vapour so if it breaks down, you could see your furnace humidifier leaking water. Your humidifier can develop clogs or cracks that can cause leaking water in your furnace or underneath.

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A Clogged Filter

Your filter plays an important role in trapping airborne particles and contaminants so they do not get into your furnace. If your furnace filter is wet, clogging or dirty, it can put an extra strain on other furnace parts because the air cannot flow properly through your appliance. This can result in excess condensation buildup and leaking water from your furnace.

Filters should be inspected regularly and changed every three months to prevent leaks and other more costly furnace repairs.

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Air Conditioner Leaking

If you have a central air conditioning unit installed, it could be the cause of your water leaking and not your furnace. Central air conditioners collect a lot of condensation within the home and remove it through condensation lines and a drain pan. If the lines or pan are clogged or damaged, your air conditioner cannot remove the moisture properly. Because the air conditioning unit is attached to your furnace, it could look like your furnace is leaking water when the actual culprit is your AC unit. At Northwind HVAC, we will inspect your AC unit thoroughly to make sure it is not causing any water leakage.

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Heat Exchanger Problem

High efficiency furnaces have built-in secondary heat exchangers to absorb the natural gases as they pass through the system. The second exchanger is installed to absorb the remaining heat that is developed by the natural gases. If there is damage or blockages in the second heat exchanger, water can leak from your furnace. A faulty heat exchanger can only be replaced by a highly qualified furnace repair technician.

Thermal Pumps for heating a house

Metal Vent Pipe is Creating Condensation

Furnaces with an AFUE under 90 have a built-in metal exhaust vent pipe to eliminate the natural gases produced when your furnace is producing heat. If you have a poor fitting or faulty exhaust vent pipe, the gas cannot escape properly so condensation will form and cause your furnace to leak water.

What Should You Do When You Notice Your Furnace Leaking Water?

Electric furnaces for heating a house

If you notice water leaking from your furnace, turn the appliance off immediately and disconnect the power source. This is especially important if you have an electric furnace because mixing the two creates a highly dangerous situation. Call us at Northwind HVAC to come inspect your furnace. We offer 24 hour service seven days a week so you can feel assured that one of our professional technicians will arrive at your place in a timely manner to troubleshoot your furnace leaking water issues.

Mop up all leaking water to make sure there is no further damage to your home. If left uncleaned, puddles of water can cause serious and costly damage to your home’s interior. Make sure the power is off before cleaning up the water to avoid injury.

Hiring Professional Furnace Repair Services

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If you notice your furnace is leaking water, contact us at North Wind HVAC immediately. Many problems that cause water leakages require a trained professional with expert knowledge in furnace troubleshooting and repair. Trying to resolve these issues on your own could cause more serious problems that could result in more dangerous and expensive repairs.

At North Wind HVAC, we have built a reputation as one of the best furnace installation, maintenance and repair companies in the area. We provide fast, reliable service competitive prices. If you have a leaking furnace, contact us immediately for all your furnace repair and servicing needs.


If you have water in your furnace, contact us at North Wind HVAC immediately. We are a furnace repair service you know you can trust.