This Is Why Water Leaking From Your Furnace In Summer!

By - Ron Singh

Updated -

Furnaces are very useful during the cold season as it works to keep your household warm and comfortable.

Although this system functions to keep you warm, it’s not uncommon for it to develop a fault at some point. As it nears summer, a common problem you would notice is a furnace water leak.

A furnace leaking water is often a condensation removal issue that surfaces as the air gets warmer.

Therefore, if you witness these leaks, you should naturally want to find the cause. Moreover, this problem can be frustrating, and you must deal with it immediately.

Keep reading to find the possible causes of a furnace leak and ways to deal with it.

A clogged internal drain is the most common reason for furnace leaks during the summer. As the environment gets hotter, your furnace air conditioner develops condensate that usually drains through a pipe unnoticed. But, when dirt or dust plugs the lines, the water will leak out of the furnace onto the floor.

Why Is Water Leaking From Furnace During Summer?

Water Leaking From Furnace In Summer

Different problems can lead to your furnace leaking water during the summer. Usually, the problems may build up long before summer and only surface through water leaks during the hot months.

In addition, the furnace type is also a determining factor, primarily if you use a high-efficiency system rather than a conventional one.

Sometimes, the problem lies with your AC rather than the furnace. If you run your AC and furnace during the same period, water from the AC condensation pan may overflow into the furnace system.

You’ve to check  If your AC and the furnace share one drain and check for blockages.

Below are the most common cause of furnace leaks during summer and possible troubleshooting suggestions:

Ten Reasons For Furnace Leaks In SummerTroubleshooting Suggestions
Clogged condensate drainClear the line of the clog
Broken condensation pipeCall a repairer to fix the holes or replace it
Holes in the drip panSeal holes with waterproof material
Broken condensation pumpFix the condensation pump or replace it
Undersized exhaust pipeCall a repairer
Clogged internal drainClear the drain pipes of blockage
Humidifier problemsCall a Professional
Overheating furnaceTurn off the furnace and call a professional
Problems with secondary heat exchangerReplace the heat exchanger or the furnace
Clogged Air filterClean  and replace your air filter regularly

Is Furnace Leaking Water Dangerous?

A furnace water leak is dangerous, and you should give it immediate attention if you notice such leaks around your furnace. It can be a danger to both you and your furnace.

The following are ways furnace leaks are dangerous:

#1. Rust

First, the build-up of moisture can result in the rusting of the metal components of your furnace. This rust will wear out these parts and make them less effective, increasing your expenses.

#2. Damage to Furnace

If water finds its way to the electrical components of your furnace, it will cause a short. This short can damage your furnace beyond repair, putting your finances in danger as the replacement cost is high.

#3. Your Health Is In Danger

Water Leaks from your furnace can put you and your household in great danger. Rust and cracks will develop when water enters the furnace heat exchanger.

These cracks can lead to gas leakage, putting you and your household in danger of Carbon-dioxide emission.

In addition, water touching the electrical parts can cause a spark which can develop a fire or lead to electric shock. Also, moisture can lead to the growth of mold, which can result in respiratory illness

How To Fix Water Leaking From Furnace In Summer?

When you notice a leak from your furnace, there are some steps you should take first before proceeding to check for the problem and fix it.

These steps can prevent further damage and remove potential dangers. Take the following steps when you notice water around your furnace:

  • Turn off your HVAC system: first, turn off your furnace air conditioner system. If you can’t find a switch, turn off the unit.
  • Mop the water on the ground 
  • Clean the water in the furnace: you can open the front covering of your furnace and clean the water, that’s if you are comfortable doing so

Below are step by step guide to fixing furnace leaks

#1. Check The Condensation Pipe

The condensation pipe is where the condensate drains pass. Most times, dirt, dust, mold, or even ice could block this channel and cause water to accumulate.

With time, this accumulated water begins to leak out of the furnace. To fix this, you have to remove the clog.

First, however, you must disassemble some parts to uncover the gas chamber to reach this PVC pipe. 

You can remove these blockages with pan tablets or blow them out with a pump. Also, you can use a small tool to push them out.

Furthermore, you should check the drain pipe for leaks. Wear and tear could lead to holes in your pipe and cause leaks.

It would help if you repaired these leaks or replaced the pipe. You should also check the condensation trap for blockages.

#2. Check The Drip Pan

The drip pan traps the condensate the furnace produces and channels it towards the condensation pipe for draining.

If this part is faulty, water will leak out from your furnace. To fix the cracks, seal the faulty part with a waterproof material, or you should replace the pan.

#3. Check The Condensation Pump

Some furnace models use a condensation pump to push the condensate through the PVC pipe. If this pump refuses to function, try switching it off and on.

Also, try to clean it properly. If after, the pump refuses to function, repair the pump or replace it entirely.

#4. Check The Exhaust Pipe

A standard-efficiency furnace doesn’t produce condensation. However, a leak can occur if your exhaust pipe is incorrectly-sized. Check out this pipe for replacement.

#5. Check The Heat Exchanger

High-efficiency furnace works with two heat exchangers. These heat exchangers work by transferring heat through the furnace system.

The furnace forms condensation in this process, and the secondary heat exchanger works to collect this condensate and drains it through the pipe. 

If this part is faulty, the furnace will produce more condensate, which leaks out. You’ll have to repair the secondary heat exchanger or change it; in most cases, you’ll have to replace your furnace

#6. Check Your Air Conditioner

If you use a furnace air conditioner during summer, most leaks from the furnace may be from the AC internal drain.

When dirt and dust block this drain, it overflows and leaks water through the furnace. Check and clean this drain regularly.

Cost Of Repairing Furnace Water Leaks 

The cost of repairing a leaky furnace differs depending on the cause of the damage and its extent. It can be costly, mainly if you’re replacing a part of the furnace.

Also, the repair cost will depend on the type of furnace you use. For example, gas and oil furnaces cost very high for repair.

The average leaky furnace repair costs range between $85 and $2100Below is a table showing the average cost of repair of a leaking furnace

Cleaning of dust and rust, including filter change$100-$300
Heat exchanger fix$100-$200
Replacement of heat exchanger$500-$1500
Condenser and evaporator coil$600-$2000


Water leaks from your furnace during summer when dirt and soot block the drainage line.

You can prevent this by inspecting and fixing your furnace regularly. You should treat a furnace water leak immediately to prevent further damage and increased cost.

In addition, always seek the help of an HVAC professional for repair and replacement.

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