Tankless Water Heater Repair: Warning Signs You Shouldn't Ignore

A tankless water heater is supposed to disappear into the wall and just work, hot water on demand, no tank to babysit. When something's off, it usually gives you a warning before it quits altogether. Catching that warning early is the difference between a quick repair and a cold shower on a Tuesday morning.

The Signs Worth Paying Attention To

• Hot water that runs out faster than it used to, or won't get as hot as it should
• Water that's hotter than you set it, or temperature that swings while you're using it
• Water that looks discolored or has an odd smell coming from the tap
• Unusual noise (banging, popping, or a hum) coming from the unit itself
• No hot water at all, even right after you turn the tap on
• Moisture, dampness, or pooling water anywhere near the unit
• Any leak around the connections or the body of the unit
• The smell of gas near the water heater. Don't try to fix it yourself: get everyone away from the area and call a licensed plumber right away, it's not a wait and see situation

Any one of these on its own might not mean much. A little noise when the unit fires up isn't unusual. But a few of them together, or any of them showing up more than once, is worth a call before it turns into a bigger repair.

Why Hard Water Makes This Worse in the Valley

Arizona's water is hard, and hard water is rougher on a tankless unit than most homeowners realize. Mineral buildup inside the heat exchanger and the internal lines is one of the more common reasons a tankless unit starts showing the signs above earlier than it should. That's part of why Majesty Plumbing's advice is that you should never install a tankless water heater unless a functioning, quality water softener system is already in place. It protects the investment you just made in the unit.

What a Standard Navien Installation Looks Like

We specialize in Navien gas tankless installations, and the craftsmanship we put into them includes copper fittings, an isolation valve kit so future maintenance is straightforward, venting sized correctly to the manufacturer's specs, an upgraded expansion tank, gas line upgrades when the job calls for it, and a wall mounted layout that's neat and easy to service. A unit installed and maintained this way tends to give you fewer surprises down the road.

Simple Maintenance That Helps

Flushing your water heater on a regular basis, tankless or tank style, helps keep mineral scale from building up in the lines. It's one of the easiest ways to stretch the life of the unit, and Majesty Plumbing recommends having a water heater serviced and flushed once a year.

When It's a Repair, Not a Replacement

A tankless unit that's throwing one or two of the warning signs above usually isn't a lost cause. Plenty of tankless issues come down to a part that needs attention, a vent that needs checking, or scale buildup that's affecting flow. The instinct to assume the worst is understandable, but it's usually worth a diagnosis before anyone starts talking about a full replacement.

What Not to Do Yourself

A tankless water heater runs on gas, electricity, and pressurized water lines, all three at once. That's not a homeowner project. If you smell gas, get everyone away from the area and call right away. If you hear repeated banging or you're getting inconsistent hot water, call a licensed plumber rather than opening the unit up yourself.

The 'Cold Water Sandwich' Explained

A common question is why a burst of cold water can show up between two draws of hot water. It's a normal side effect of how a tankless unit works, sometimes called the cold water sandwich effect: water left sitting in the line from the last use cools down while the unit resets, then gets pushed through before fresh hot water catches up behind it. It's more noticeable on some layouts than others, and on its own it's not a sign anything's wrong.

We work on tankless systems throughout Queen Creek, San Tan Valley, Florence, Gold Canyon, Apache Junction, Mesa, Gilbert, Tempe, Chandler and Phoenix.

If your tankless water heater is showing any of these signs, Majesty Plumbing has served the East Valley since 2007, specializes in Navien gas tankless installations, and has technicians with over 30 years of field experience. Give us a call at (480) 677-2221.