First steps
- Protect yourself.Keep water away from the unit's power cord and outlet. If anything electrical is wet, do not touch it; shut off the circuit at the panel if you can do so safely.
- Stop the water.Close the cold-water service valve below the unit. If there is no valve or it will not close, shut off water at the home's main.
- Shut down the unit.Turn off the unit and close its gas valve, following the manual.
- Find the source.Dry the area and watch where water reappears: a fitting, a valve handle, the relief valve outlet, the condensate line or inside the cabinet.
- Call a licensed plumber.Share what you found, along with the model number and any error code.
Leak sources and what they mean
| Where the water is | Common cause | Urgency |
|---|---|---|
| Threaded fitting or union | Loose or corroded connection | Moderate; often a straightforward repair |
| Service valve stem or flush port cap | Worn packing or a cap left loose after flushing | Moderate |
| Pressure relief valve outlet | High pressure, overheating or a failing valve | High; have it checked promptly |
| Condensate line | Clogged or disconnected drain on a condensing unit | Moderate; can damage walls or floors |
| Inside the cabinet | Heat exchanger or internal fitting leak | High; stop using the unit until inspected |
Why leaks show up in Fullerton installs
Hard water leaves mineral deposits on valve seats and threads, and those deposits can keep a valve from sealing or a cap from seating. Older homes with galvanized supply lines can also send rust and debris toward the unit, wearing valves faster.
High house water pressure is another factor. If your home's pressure is high, a plumber may suggest checking or installing a pressure regulator, and an expansion tank where the plumbing calls for one. Those questions are worth asking whenever a relief valve has been discharging.
Repair or bigger job?
Usually a repair
- Loose union or fitting
- Worn service valve or flush cap
- Clogged condensate line
- Relief valve replacement after the cause is found
May point to replacement
- Leaking heat exchanger
- Corrosion inside the cabinet
- Repeated internal leaks on an older unit
- Damage from freezing on an exterior unit
Ask the plumber
- Exactly where is the leak coming from?
- Is the house water pressure within a safe range?
- If the heat exchanger is leaking, is it under warranty?
- Did the leak damage the wall or floor in a way I should check?
Common questions
Is a small drip from the flush port urgent?
Usually not dangerous, but it wastes water and can corrode nearby parts. Tighten or replace the cap, or have the valve checked.
Can I keep using the unit while it leaks?
If the leak is inside the cabinet or at the relief valve, stop using it until a licensed plumber inspects it.
Where is my main shutoff?
In many Fullerton homes it is near where the water line enters the house or at the meter box. Find it before you need it.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.