Why is my heat pump leaking water indoors?
If your indoor heat pump head is dripping, shut it off first. Here's what's causing it and what to do next.
Why heat pumps create water
When a heat pump cools your home, warm indoor air passes over a cold coil. Moisture in the air condenses on the coil, similar to water forming on a cold drink glass. That water should flow into the drain pan and out through the drain line.
If the drain path is blocked or dirty, water can back up and leak from the indoor head. ENERGY STAR includes condensate drain inspection as part of a typical HVAC maintenance check because a plugged drain can cause water damage and affect indoor humidity.
Common causes of indoor water leaks
Indoor heat pump leaks are most often caused by a clogged drain channel, blocked drain line, dirty indoor coil, poor slope from installation, cracked drain pan, frozen coil thawing, heavy humidity load, or dirty filters reducing airflow.
Cleaning can resolve the issue when it is caused by dirt, slime, debris, or buildup in the drain area.
Why dirty filters make leaks worse
Dirty filters restrict airflow. Poor airflow can make the coil too cold in certain conditions, which can contribute to condensation or icing problems. Once ice melts, the water may overwhelm the drain path.
Natural Resources Canada says clogged filters decrease airflow and reduce heat pump efficiency — and the knock-on effects go beyond comfort.
What to do right away
Turn the unit off. Place a towel or container under the leak. Check whether the filters are visibly dirty. Do not keep running the system to see if it clears. Book a professional inspection and cleaning.
Do not take apart the unit unless you know what you are doing. Manufacturer guidance warns that improper internal cleaning can cause damage, water leakage, or electrical hazards.
When cleaning solves the problem
Cleaning may solve the leak if the drain channel is dirty, the filters are clogged, the coil is grimy, or airflow has been restricted by buildup. A professional can clean the indoor head and confirm that water is draining correctly.
If the leak is caused by installation slope, damaged parts, refrigerant issues, or a cracked drain pan, repair may be needed instead of cleaning alone.
Common questions
- Is a leaking heat pump an emergency?
- Turn it off immediately. Even a slow drip can cause wall and flooring damage quickly. Don't leave a leaking unit running.
- Can I unblock the drain myself?
- You can try gently flushing the drain line with warm water, but the drain pan and channel inside the unit need disassembly to clean properly.
- Does a water leak mean the heat pump needs replacing?
- Usually no. Most indoor leaks are maintenance issues — drain blockages and dirty coils — not equipment failures. A professional clean resolves the majority of cases.
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