Tankless water heater service in Los Angeles for scale, error codes and cold bursts

We start by shutting off gas and power, closing the hot and cold isolation valves under the unit, and opening the purge ports. A small submersible pump then circulates a food-grade descaling solution, usually citric or vinegar based, through the heat exchanger for about an hour.

After the flush we rinse with fresh water, pull and clean the inlet screen, and check the flow sensor for buildup. Then we restart the unit, watch the flame, take a temperature reading at the nearest tap and confirm the heater fires at the flow the manufacturer expects.

Some heaters were installed with no isolation valves, which leaves nowhere to hook up the pump. In that case we fit a service valve kit first. It turns every later flush into a short visit instead of a cut-and-solder job.

Most manufacturer schedules assume moderate water. LADWP and many neighboring water departments deliver Colorado River and State Water Project supplies, both carrying dissolved calcium and magnesium. A tankless exchanger has narrow passages and heats water in seconds, which is exactly the condition that drops minerals out of solution and bakes them onto the metal.

A tank heater hides scale at the bottom of the tank for years. A tankless unit shows it within months as weaker flow, higher exhaust temperature and overheat codes. A softener slows the buildup a great deal, though we still look at the exchanger once a year. Our guide to what hard water does in LA homes explains the chemistry in plain terms. High temperature settings speed up scaling too, so a lower setpoint helps.

Not every tankless complaint is scale. A unit that clicks but never lights may have a worn igniter, a dirty flame rod or a gas valve that will not open. We test each part instead of swapping them on a guess, and we carry common igniters and sensors for the brands we see most in LA garages.

Gas supply is a frequent hidden cause. A tankless heater can demand far more gas at full fire than the old tank did, and homes that were never upsized starve the burner when the dryer and furnace run at the same time. We measure pressure at the unit under full load, and if the pipe is undersized our gas line repair work can bring it up to size.

• Igniter and flame rod cleaning or replacement
• Flow sensor and inlet screen cleaning
• Vent checks for blocked or separated joints
• Condensate neutralizer and drain line replacement
• Combustion fan and circuit board diagnosis

Heat exchangers do fail, usually from scale overheating the metal or from corrosion on a unit that was never flushed. On an older heater, a replacement exchanger can cost a large share of a new one. We put both numbers side by side so you decide with real figures in front of you.

If you lean toward replacing, our tankless installation work covers sizing, venting and gas upgrades. Some homeowners go back to a tank or switch to a heat pump instead, and our article on tank, tankless and heat pump tradeoffs lays out the differences.

Condensing models deserve their own note. They produce acidic condensate that has to pass through a neutralizer before it reaches a drain. Once the neutralizer media is spent, that acid etches drain lines and concrete, so we check and refill it on every visit.