Why Is My Gas Furnace Leaking Water? A California Tech Explains
If you’ve recently noticed water leaking from your furnace, you’re probably wondering why, and more importantly, how to fix it.
The answer to both of these questions depends on whether you have a high-efficiency (condensing) furnace or a conventional (non-condensing) furnace.
If you have a conventional (non-condensing) furnace, your system will have a metal vent pipe, and your furnace is likely leaking due to:
- An improperly designed flue pipe
- Damaged/malfunctioning humidifier
- A clog in the drain pan or condensate line
- Damaged condensate pump
Below, we’ll look at why both a conventional and a high-efficiency furnace may leak, as well as the steps you can take to stop leaking and prevent it going forward.
WHY A CONVENTIONAL (NON-CONDENSING) FURNACE CAN LEAK
As we mentioned above, your conventional furnace is likely leaking because of the following:
- Flue pipe
- Humidifier
Leakage from the Flue Pipe
Flue pipes are designed to carry the gases your furnace produces out of your home before they have time to cool down and condense into water.
However, if your flue pipe is damaged or was installed incorrectly (no slope or too large), it may prevent those gases from exiting your home before they cool down. If your flue pipe isn’t designed correctly, those gases can condense inside the flue pipe and drip back down toward the furnace.
If you think this may be the issue you’re experiencing, reach out to a professional. They will be able to check out your furnace and determine if your flue pipe needs replacing. This issue can often lead to what looks like a furnace pipe leaking water, which requires immediate attention.
LEAKAGE FROM THE HUMIDIFIER
Your furnace may have a humidifier attached to it, which adds moisture to your home’s air.
However, if your humidifier is clogged or damaged, the water circulating in it can leak out and pool around the bottom of your furnace, causing the leak you’re noticing.
If you think it’s your humidifier (rather than your actual furnace) that’s leaking, reach out to a technician. They should be able to quickly determine what the issue is and unclog or fix your humidifier. If left unchecked, this might resemble a gas furnace leaking water, requiring a thorough inspection.
Why a High-Efficiency (Condensing) Furnace Can Leak
Unlike conventional furnaces, high-efficiency (condensing) furnaces are meant to produce condensation (hence why they’re called condensing furnaces).
Why?
High-efficiency furnaces have 2 heat exchangers rather than the 1 heat exchanger a conventional furnace has.
Instead of traveling through 1 heat exchanger and then out through the flue pipe, gas in a condensing furnace travels through 2 heat exchangers, which means it has time to cool down by the end of the heating cycle.
In a perfect world, this gas will condense and drain out of your home via the condensate drain.
However, if there are clogs along the condensate line or an issue with the condensate pump, you may find yourself wondering why is my furnace leaking water from the bottom, as condensation can spill onto the ground or into the attic, potentially causing damage to your floor or ceiling.
Blocked Condensate Drain Trap
Your drain trap is in place to prevent gases from escaping through the drain line. Over time, it can become clogged, and prevent condensation from draining properly and exiting your home leading to issues like a gas furnace leaking water. Before calling a professional, check your drain trap. If it’s clogged, you can try to unclog it using a shop vac. However, if this doesn’t work, you should reach out to a professional for help.
Clogged Condensation Line
The condensation line is the part of your system that connects the drain trap to the outside of your home. If there is a clog in any part of this line, condensation can back up and result in a furnace pipe leaking water which could overflow onto your floor or into your attic. Because clogged condensation lines are a little more difficult to fix, our advice would be to call a professional rather than attempt this fix on your own.
Condensate Pump Issue
The condensate pump is a small pump attached to the drain line of your furnace. This pump works to push water into a drain or outside. However, if this pump is damaged or malfunctioning, the water may leak and spill out onto your floor or into your attic. You’ll probably be able to tell if this is your issue because if your condensate pump is leaking, water will usually leak from the pump itself. You’ll need to call a professional to come and fix your condensate pump.
Additional Issues That May Cause Leaks
Leaks from your furnace may not always come from the primary causes listed above. Other issues include:
Heat Exchanger Damage
A cracked heat exchanger can cause a gas furnace leaking water or condensation to leak out of your furnace. This is a serious issue that often requires immediate attention and possible replacement of the heat exchanger.
Cracked Pipe
A cracked or damaged pipe connected to your furnace’s drainage system can result in water pooling around the base of the unit.
Loose Connection
A loose connection in the condensate line or other parts of the furnace drainage system can cause leaks. Tightening or repairing these connections is usually a quick fix for a professional.
What to Do When Leaks Occur
If your gas furnace is leaking water, here’s what you can do:
- Turn off your furnace to prevent further damage.
- Try to identify the source of the leak (flue pipe, condensate line, etc.).
- Contact a professional for a thorough inspection and repair.
Leaks, whether from a furnace pipe leaking water or other issues, can escalate quickly if not addressed promptly. If you’re wondering, “why is my furnace leaking water from the bottom”, it’s essential to act fast to avoid further complications.
Fix Your Furnace Leak with Burgeson’s
If you’re still having issues with a leaking furnace, reach out to us. We understand that dealing with a leaking furnace can be stressful, but it doesn’t have to be.
We have over 76 years of experience helping homeowners in Southern California with HVAC maintenance as well as heating system repair, and we’d be happy to help you too. When you’re ready, you can schedule an appointment.
