Tankless Water Heater Repair in Knoxville, TN

Most tankless units we get called out for aren’t broken. They’re dirty.

That’s the short answer, and it saves people a lot of money once they hear it.

Here’s the longer version.

What’s Happening Inside

Knoxville sits on hard water. Roughly five grains of dissolved minerals per gallon.

Those minerals don’t disappear when the water gets heated. They come out of solution and stick to whatever they touch. Inside a tankless unit, what they touch is the heat exchanger — the narrow metal channels your water travels through while a burner heats it.

Scale builds on those walls slowly. A film after a year. A shell after several.

Once that shell is thick enough, the burner can’t transfer heat into the water fast enough. You feel that as lukewarm output, or heat that comes and goes, or a unit that shuts down under load.

The equipment is fine. The passage is obstructed.

What You Notice First

Water temperature that swings during a single shower.

Clicking or repeated ignition attempts when you open a hot tap.

An error code on the display panel.

Output that’s strong for the first minute and weak after.

The unit dropping out when a second fixture runs.

Slow delivery, which is often a plugged inlet screen rather than the exchanger at all.

What It Takes to Fix

A descaling flush, most of the time.

A pump circulates solution through the exchanger for about an hour and dissolves the mineral deposits. We clean the inlet screen and air filter, check the venting, and read the stored fault history while we’re in the unit.

Total time is usually two hours.

Replacement is the right answer sometimes. A cracked exchanger, a failed control board on an older unit, a system that was undersized for the house from day one. We’ll tell you when that’s the case and show you what we’re looking at.

But scale accounts for most of the service calls we run on these.

Maintenance Interval

Annually, in this water.

Manufacturer manuals often say every two years. Those intervals assume average water hardness nationally, which isn’t what we have.

Two things depend on staying current. First, performance — a unit flushed on schedule holds its output. Second, warranty coverage. Most manufacturers require documented annual service, and they enforce it. If you file a claim after six years with no service records, expect to be declined.

An hour on the calendar once a year is the whole ask.

Service Life

A maintained tankless unit lasts twenty years or more.

A neglected one fails around eight to ten.

That gap isn’t about brand or price. It’s entirely about whether the exchanger stayed clean.

How We Work

We diagnose first. Codes, exchanger condition, water pressure, venting.

Then you get the finding and the estimate before anything gets done. If a flush solves it, that’s great. If the unit is finished, we’ll show you the failure and walk you through what makes sense from there.

Common Questions

Why does my tankless unit go cold mid-shower?

Usually scale on the heat exchanger. Ignition and venting problems cause it too. Brief temperature variation at startup is normal on any tankless system; a drop after you’re already running is not.

How often should it be flushed?

Once a year for sure.

Should I worry about clicking?

It indicates the igniter is struggling. It isn’t urgent, but it typically precedes ignition failure. Address it before it stops lighting.

Can I do the flush myself?

It’s possible with a pump, hoses, descaling solution, and knowledge of your isolation valves. Verify your warranty terms first — self-performed service often doesn’t satisfy the documentation requirement.

Does hard water actually shorten the life of the unit?

Significantly. Scale forces the exchanger to run hotter than design temperature, which fatigues the metal. A water softener addresses the cause rather than the symptom.

Call Bizzy B at (865) 233-3900 for tankless service in Knoxville and Blount County.