How a tankless heater works, and who it suits
A tankless water heater heats water on demand as it passes through a heat exchanger, so there is no tank to run dry. It suits households that run back-to-back showers and want to free floor space. The trade-offs are a larger gas or electric load, careful venting and regular maintenance.
Most of the calls we hear fall into three groups: owners who need a flush, owners with an error code, and owners deciding whether to switch from a tank. This page follows that order.
Flushing and descaling the heat exchanger
Brigham City's own water page lists hardness at 17 to 20 grains per gallon. In a tankless unit, that mineral load settles inside narrow passages of the heat exchanger and slowly chokes flow, which shows up as lukewarm water, noisy operation and error codes. A scaled exchanger can shorten the life of an otherwise good unit.
- Isolate the unit
Close the gas and cold water, and shut the hot outlet so the unit can be drained safely.
- Connect the flush kit
A small pump and a bucket circulate a descaling solution through the exchanger.
- Circulate
The solution runs for a set time, depending on how scaled the unit is.
- Rinse and clean the filter
Fresh water flushes out loosened scale, and the inlet screen gets cleaned.
- Restore and test
We reopen the valves, fire the unit and watch temperature and flow.
A yearly flush beats waiting for a warning code. A water softener ahead of the unit cuts the build-up, though ask Public Works for the current hardness before sizing it.
Error codes and what they usually point to
Codes differ by maker, so read your manual for the exact meaning. Callers often mention two-digit codes in the low teens, and the cause usually falls into a few families.
| What you see | Likely family | Safe to try first? |
|---|---|---|
| Ignition or flame code | Gas supply, igniter or flame sensor | Check that the gas valve is open, then stop. |
| Lukewarm output, no code | Scale in the exchanger or a clogged inlet screen | Clean the screen if the manual allows. |
| Flow or low-flow code | Aerators, filters or a partly closed valve | Yes, check valves and aerators. |
| Vent or exhaust code | Blocked vent, disconnected pipe or bird nest | No, call a technician. |
| Repeated shutoff, burnt smell | Wiring or an overheated component | No, power it off and call. |
Service does not always mean replacement. Many units are repairable, and we say so honestly when a part or a flush solves the problem.
Lukewarm water or a flashing code?
Scale is a common cause, and a flush often helps.
Sizing: flow rate and gas supply
Tankless sizing is about flow, not tank gallons. Add up the fixtures that may run at once, then match the temperature rise your incoming water needs. Cold winter inlet water means the unit works harder, so ask the installer to size for your coldest months.
- Check the gas meter and the gas line size, because many tankless units demand more fuel than a tank.
- A line that is too small starves the burner and triggers shutoffs.
- Count showers, the dishwasher and the washer, not square footage.
- Confirm the vent route and clearance before you pick a model.
Our water heater installation page covers venting and layout, and plumbing installation work handles the gas and water lines.
Switching from a tank to tankless
A conversion is bigger than a like-for-like swap. Expect a new vent, possibly a bigger gas line, a condensate drain on condensing models, and an outlet for the unit's electronics. A pressure relief and a service valve kit make future flushing easy.
Permit rules vary, so ask the Brigham City building office at (435) 734-6604 before starting. If you smell gas at any point, leave first, then call 911 or the gas utility.
Repair or replace: the service-not-just-replace worry
Some installers only want to replace. We start by finding the actual fault, whether that is a sensor, a flow switch, a control board or scale. If the exchanger is cracked or a repair would cost close to a new unit, we say so. If a flush or a part brings the unit back, that is what we do first.
Our water heater repair page lists other diagnostics that apply to any heater, including leak checks.
What affects the cost of tankless work
Service versus install
A flush is a short visit, while a conversion can take a day or more.
Gas line and vent work
Upsizing the line or running a new vent adds time.
Scale level
A heavily scaled unit needs longer circulation.
Access
Wall-mounted units in tight spaces are slower to service.
Parts
Boards, sensors and fans vary by maker.
Insurance rarely covers a planned conversion or scale damage. Want your real number? Call (855) 575-2890 and you get a clear price before work starts.
Help for owners from Tremonton to Brigham City
Our crews work out of 647 S Main St in Brigham City, and Tremonton plumbing service sits about 20 miles north. Tell dispatch the make, the age and the code on the display, because that shortens the diagnosis. Dispatch is 24/7 if the unit leaks or smells of gas. A pure comfort complaint can wait for a daytime visit.
Frequently Asked Questions
Many makers suggest a yearly flush, and the city lists very hard water at 17 to 20 grains per gallon. Check your manual and book a flush before scale causes errors.
Often, yes. We find the fault first, whether that is a sensor, a filter, a flow issue or scale, and explain whether a repair makes sense.
Codes differ by maker, so your manual gives the exact meaning. Most fall into ignition, flow, vent or temperature families.
It can be, if sizing and gas supply are right. Peak demand and your local water hardness matter more than the house's size.
Often. Tankless units can need more fuel at once than a tank, so the line size is checked first.
Yes. Dispatch is 24/7. Close the water to the unit and turn off the power while you wait.
Sources and standards
- Plumbing codes in the UPC and IPC families set the rules for fixtures, venting and drains. Ask the Brigham City building office at (435) 734-6604 which edition and permit rules apply to your job.
- The Utah Division of Professional Licensing offers a public Verify a License tool for checking any plumber's license class.
- The Brigham City Water Division explains hardness, pressure testing and water quality on its water page. Call Public Works at (435) 734-6615 with questions.
- Enbridge Gas Utah says to leave the building first if you smell gas, then call 911 or its 24-hour emergency line from outside.
Written by Brigham City Pro Plumbing. Last updated October 29, 2026.