‘It’s tankless — what could leak?’ Plenty, as it turns out. No tank means no tank rupture, but a tankless unit is still a box full of water connections, valves, seals, and a condensate drain. Here are the usual suspects, in the order we actually find them.
The water connections
Start simple: the hot and cold connections at the unit can weep like any fitting, especially after years of thermal cycling. If the drip is at the wall connections or the service valves, that is plumbing, not the heater — and usually a straightforward fix.
Condensate problems
High-efficiency condensing units produce acidic condensate that must drain away through a dedicated line. When that line clogs — or the neutralizer cartridge clogs with it — water backs up inside the cabinet and drips out the bottom. If the puddle is under the unit and the condensate line looks suspect, you have probably found it.
Isolation and service valves
Tankless units have isolation valves for flushing and service. Their packing and seals weep with age, particularly in hard water. A slow drip at a service valve is common and fixable — but do not overtighten it yourself; those valves crack.
Scale: the desert’s favorite tankless killer
Apache Junction water leaves mineral scale inside the heat exchanger. Scale restricts flow, creates hot spots, and stresses seals and sensors — and neglected scale is behind a large share of the tankless leaks we see. Regular descaling is not optional maintenance here; it is what keeps the unit from eating itself.
Heat-exchanger seals
After years of heating cycles in mineral-heavy water, the seals in the heat exchanger can start to seep. This one is a technician diagnosis — it looks like water appearing inside the cabinet with no obvious fitting source. If you see that, shut the water off at the isolation valves and call (833) 713-2101.