Drips From a Wall-Mounted Tankless Unit

Where tankless units leak

• Condensate drain line (condensing gas models): a plastic line that carries acidic condensate to a drain. It can clog, sag or pop off.
• Service valves under the unit: the hot, cold and sometimes gas valves with flush ports. Their caps and packings can drip, especially after a flush.
• Water connections: unions and flexible lines can loosen with heat cycling.
• Pressure relief valve: many installations include one; it can weep if pressure runs high.
• Heat exchanger: water dripping inside the cabinet can mean the exchanger itself has cracked or corroded.

Hard water and scale

Westfield’s Citizens water averages about 22 grains per gallon. In a tankless heater, those minerals bake onto the inside of the heat exchanger as scale. Scale cuts flow, makes the unit run hotter and is a frequent reason exchangers fail early. ENERGY STAR’s 20-year life expectancy assumes reasonable care, which in hard-water homes usually means regular flushing or softened water.

Winter freeze risk

Central Indiana winters bring extended freezing weather. Units on exterior walls, in garages or with exterior venting can freeze if power is lost or the freeze protection fails, cracking internal parts. Leaks that start after a cold snap or a power outage are worth mentioning on the call.

Safety for gas tankless units

If water has reached the burner or vent connections, turn the unit off and close the gas valve. A damaged vent on a gas appliance can let carbon monoxide into the home, so keep a working CO alarm nearby. If you smell gas, leave and call from outside.

What to tell the provider

Give the brand and model if you can see it, any error code, whether it is gas or electric, where the drip is, and whether the unit was recently flushed or exposed to freezing.