Tankless water heater maintenance comes down to four jobs done about once a year: flushing the heat exchanger with a descaling solution, cleaning the inlet filter, checking that the vent is clear and sound, and reading the unit's error history. Skipping them does not cause trouble overnight, but scale and clogs build slowly and show up as weaker flow, noisy operation and error codes.
Below is each task in general terms, how often to do it, and the point where a licensed plumber should take over. If you do not have a tankless unit yet, our tankless installation and sizing page explains both, and the owner's manual for your model always has the final word on intervals.
Signs your tankless unit is due for service
These symptoms often appear before an outright failure, and they usually mean scale or a restriction rather than a dead heater.
- Hot water that takes longer to arrive or runs hotter and colder than usualScale on the heat exchanger makes the unit work harder to hit its set temperature.
- Weaker flow at the hot taps onlyA clogged inlet screen or scaled heat exchanger restricts water through the unit. If cold flow is normal, the heater is the likely restriction.
- A new rumbling, popping or kettle-like soundMineral buildup can cause small pockets of boiling, which sounds like a kettle starting up.
- An error code that returns after you reset itA code that appears once may be a fluke. One that keeps coming back is the unit telling you what to look at.
- Visible corrosion or discoloration on the vent pipeA vent that looks different from last year deserves a closer look before anything else on this list.
What to do and how often
Your owner's manual sets the real schedule, and these are the common baselines. Use it as a way to organize the work rather than as a replacement for the manual.
| Task | Typical interval | Can an owner do it | Call a plumber if |
|---|---|---|---|
| Descaling flush of the heat exchanger | About once a year, sooner if scale builds fast | Often, with service valves installed | No service valves exist, or hoses will not connect cleanly |
| Inlet filter cleaning | At least once a year | Usually | The housing is stuck or leaks after closing |
| Vent check | Once a year, by eye | Looking only, not repairs | You see gaps, rust, blockage or loose joints |
| Error history review | Once a year, or after any repeat code | Yes, using the display and manual | The same code returns or involves gas or ignition |
| Gas and combustion check | As the manual directs | No | Always, and immediately if you smell gas |
The yearly descaling flush, in general terms
The flush circulates a descaling solution through the unit to dissolve mineral buildup. The details differ by model, so follow the manual's solution type, volume and timing. The outline below shows the typical order.
Turn off power and gas, and close the water valves
Switch off the unit's power and close the gas supply. Close the cold inlet and hot outlet service valves. Let the unit cool, because water inside can be hot enough to scald.
Connect the hoses to the service ports
Attach one hose to the cold side port and another to the hot side port, then run the discharge hose to a bucket. Check that every connection is snug before opening anything.
Circulate the solution
Open the ports and run a small pump to push the solution through the heat exchanger for the length of time the manual gives. Watch the bucket for cloudy water, which is dissolved scale.
Rinse with fresh water
Close the solution loop, open the cold inlet and run clean water through until the discharge looks clear. Rinse longer than seems necessary, because residue should not reach your taps.
Close the ports and restore everything
Remove the hoses, close the service ports, reopen the inlet and outlet valves, and restore power and gas. Run a hot tap for a minute and check for leaks.
If the gas valve will not shut fully, if a service port leaks, or if you smell gas at any point, stop. Step outside, dial 911, contact your gas utility, and only then phone a plumber.
Filter, vent and error history
These three checks take less time than the flush and tell you a lot about the unit's health. Do them at the same visit and note what you find for next year.
Cleaning the inlet filter
The inlet filter is a small screen at the cold water connection that catches grit before it reaches the heat exchanger. Close the inlet valve and relieve pressure at a hot tap, unscrew the housing, rinse the screen under water and reinstall it. A screen packed with debris cuts flow and forces the unit to work harder.
Checking the vent
Look at the vent pipe along its whole visible run and at the outdoor termination. You are checking for blockage, loose joints, corrosion and anything resting against the opening. Do not repair or reseal vents yourself. A faulty vent can let exhaust back into the home, and that is a licensed plumber's job.
Reading the error history
Most units store recent fault codes, and the manual explains how to display them. A pattern, such as repeated ignition or exhaust codes, tells a plumber much more than a single reset does. Write the codes down before you clear anything.
Your tap water and tankless scale in Hallandale Beach
The City of Hallandale Beach publishes an annual water quality report, and chloramines are the disinfectant named in the 2025 report. Chloramines are not what builds scale. Hardness is, and the city's own utility page says it softens water at the plant but none of its published reports gives a hardness number.
That leaves you with two practical options. Test your tap with a hardness test kit, or ask the Utilities Division, which runs the water system under Public Works, what it can tell you about your supply. Then set your flush interval accordingly, and shorten it if you find scale on the inlet screen. If the screen is clean year after year, you have good evidence the interval is adequate.
When a plumber should do it
Bring in a licensed plumber in four cases. The unit has no service valves. The flush has never been done and the unit is several years old. The same error keeps coming back. Or anything involves the gas supply, the vent or the condensate drain. Some manufacturers require documented service to keep warranty coverage, so check your paperwork first.
A service call can also tell you whether the heat exchanger is worth saving. Our water heater repair team works on tankless units, and for a home with heavily scaled lines, water softener and filtration is worth a conversation.
Neighbors who ask the same questions
Tankless owners in nearby communities ask us the same things, from condo owners in Hollywood plumbing territory to homes served by plumbers serving Aventura. The maintenance steps do not change by town, but the water does, so test your own tap and follow your own manual.
A yearly maintenance visit takes much less time than an emergency one, and it is easy to put on the calendar next to the smoke detector batteries.
Questions homeowners ask
Use the type and amount your unit's manual calls for. Some manufacturers allow household vinegar and others name their own descaler, and the wrong solution can damage seals or the heat exchanger.
About once a year is the common baseline. Because the city's reports do not list a hardness figure, test your tap or ask the Utilities Division, then check the inlet screen for scale and shorten the interval if you find any.
You can, for a while. Scale builds slowly, so the heater may run normally until it suddenly does not. A yearly flush is cheap insurance next to a heat exchanger replacement.
Yes, they make the job practical. Without them, a plumber can add them, and that is a worthwhile upgrade on any unit that will be flushed for years.
A reset is fine for a one-time fault. If the code returns, or if it involves ignition, flame or exhaust, leave it alone and call a plumber. If you smell gas, leave the building and call 911.
No. A softener reduces scale but does not remove the need to check the filter, vent and error history. It can lengthen the interval between flushes, and the manual and your tap test should guide that.
Sources and official references
The governing standard for plumbing work in Florida is the Florida Building Code, Plumbing (8th Edition, 2023), with the 9th Edition scheduled to take effect December 31, 2026. This page is general information and not a code interpretation, so confirm requirements with the city Building Division.