A tankless water heater lasts 20 years or more in Houston, about double the life of a tank, on one condition: it gets descaled once a year. Skip that, and Houston’s hard water can cut its life to 8 to 10 years, no better than the tank it replaced.
Why Tankless Lasts Longer
A tank water heater dies when its steel tank rusts through, and nothing can fix that. A tankless unit has no tank. Water passes through a copper or stainless heat exchanger only when a tap opens, so there is no standing water corroding a vessel around the clock. Its parts, such as the flow sensor, igniter, fan, gas valve, and control board, are replaceable, and manufacturers typically warranty the heat exchanger for 10 to 15 years. The result is a unit that ages by wear and neglect rather than by an inevitable failure date.
What Kills Tankless Units in Houston
Scale. Houston water carries enough calcium and magnesium to coat the inside of the heat exchanger. Scale insulates the copper, so the burner runs hotter and longer to hit the set temperature, efficiency drops, and eventually the exchanger overheats or cracks. This is the number one cause of early tankless failure here, and it is entirely preventable. See how Houston hard water damages plumbing.
Undersized gas supply. A tankless unit needs far more BTUs than a tank. If the conversion reused the old gas line, the unit starves under load, cycles, and throws error codes. It also shortens the life of the igniter and gas valve.
Poor venting or combustion air. Condensing units need the right vent material and a working condensate drain. Blocked or improperly sloped vents cause shutdowns and corrode the unit from the inside.
Attic heat. Electronics do not love 130°F summers. A tankless unit installed in an attic runs fine but benefits from a shaded, ventilated location where possible.
Signs Yours Needs Attention
- Hot water that goes lukewarm or alternates hot and cold with two fixtures running.
- Reduced flow at hot taps while cold flow is normal.
- Error codes on the display, especially for temperature, flow, or ignition.
- A longer wait for hot water than when the unit was new.
- Rattling, whining, or kettling from the heat exchanger.
Most of these are scale. A descaling flush usually restores performance the same day. If the unit is starving for gas or short-cycling, that is an install problem, and it is worth a free look from a licensed plumber. Our no hot water troubleshooting guide covers the quick checks.
The One Thing: Annual Descaling
Descaling means isolating the unit with its service valves, circulating a descaling solution through the heat exchanger with a small pump for 45 to 60 minutes, then flushing with fresh water. Units installed with proper isolation valves make this an easy annual job. Units installed without them have to be partly disassembled, which is why we always install service valves. Descaling is part of our water heater maintenance service, and we clean the inlet filter, check the venting and condensate drain, and read the error history while we are there.
Buying Time or Buying New
A well-maintained tankless unit at 15 years is usually worth repairing. A neglected one at 10 with a leaking heat exchanger usually is not, since the exchanger is most of the unit’s cost. When it is time, Hugo Plumbing installs gas and electric tankless units and does tank-to-tankless conversions with the gas line, venting, and permit handled. Pricing depends on whether it is a straight replacement or a conversion, so we quote it in writing after a free visit. Our $200 high-efficiency water heater coupon applies and financing options are available. See tankless water heater installation and our tank vs. tankless comparison.
If your tankless is due for its flush, call Hugo.
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