What should I do if my tankless water heater needs repairs?

Question

Accepted Answer

Note the error code on the display before doing anything else — it tells a technician most of what they need to know. Then check the basics: gas supply, power, and the inlet filter screen. If those are fine, call. We repair tankless units 24/7 across the Albuquerque metro.

Before You Call

Write down the error code. Tankless units self-diagnose, and the code narrows the cause immediately. Photograph the display if you can.
Confirm gas and power. Check that other gas appliances work and that the unit’s breaker has not tripped. Reset once; if it trips again, stop.
Check the inlet filter screen. A sediment-clogged screen restricts flow and can mimic a much larger problem. This is a common and cheap fix.
Check venting for visible obstruction — bird nests and debris cause lockouts more often than you would expect.

The Most Common Failures Here

Scale in the heat exchanger. The leading cause of tankless problems in Albuquerque. Presents as reduced output, fluctuating temperature, error codes, or the unit shutting down mid-shower. Usually resolved by descaling if caught before the exchanger is damaged.
Flow sensor problems. The unit does not fire or cycles on and off during use.
Igniter or flame sensor failure. No hot water at all.
Venting obstruction or condensate blockage, triggering a safety lockout.
Undersized gas supply, which shows up as the unit failing under high demand while working fine on a single fixture.

The “Cold Water Sandwich”

A brief cold burst when hot water restarts after a short pause. This is characteristic of how tankless units work rather than a fault, though a recirculation loop or buffer tank can reduce it.

Most Repairs Are Component-Level

Unlike a tank, where a corroded body means full replacement, tankless components are individually serviceable — heat exchangers, sensors, igniters, and boards can all be replaced. That is a real part of the value proposition.