Heat Pump Leaking Water: Causes & What to Do

Normal Water From a Heat Pump

Some water production around a heat pump is completely normal:

• Condensate during operation: As the evaporator coil cools air, moisture condenses on the coil and drips to a drain tray. This is normal and should be directed to a drain.
• Defrost water: During the defrost cycle, ice on the evaporator melts and runs off. Significant water can flow from the base of the unit during defrost.
• Steam during defrost: On cold days, the hot defrost cycle can produce visible steam. This is normal.

Causes for Concern

• Blocked condensate drain: If the drain tray overflows, water may appear around the base of the indoor unit or in the airing cupboard. Clear the drain pipe of any blockages.
• Water from indoor unit ceiling mount: Water dripping from an indoor fan coil unit ceiling suggests a blocked drain or failed drain pump.
• Water around indoor hydrobox: Could indicate a leak on the hot water side of the system (heating circuit or DHW cylinder). Check all pipe connections.
• Ice forming and melting at outdoor connections: Could indicate a refrigerant leak at a flare fitting.

What to Do

If you see water in unexpected locations, switch off the system and call an engineer. Water damage can escalate quickly if left unaddressed. In the meantime, protect floors and carpets with towels or buckets as needed.