Everything You Need to Know About Tankless Water Heater Maintenance

Why Tankless Water Heater Maintenance Requirements Matter More Than You Think

Tankless water heater maintenance requirements include a core set of upkeep tasks every homeowner should know — here’s a quick overview:

Tankless water heaters are one of the best upgrades a Southern California homeowner can make. They deliver hot water on demand, take up less space, and can be 24%–34% more energy efficient than traditional tank-style units — but only when they’re properly maintained.

Here’s the problem: a lot of homeowners assume “tankless” means “maintenance-free.” It doesn’t. Without regular upkeep, mineral scale quietly builds up inside the heat exchanger, choking flow and forcing the unit to work harder. Over time, that leads to higher energy bills, inconsistent hot water, and — if left long enough — a premature breakdown that costs far more to fix than routine service ever would.

Think of it the way you’d think about oil changes for your car. Skip them long enough, and you’re not just dealing with a minor inconvenience — you’re looking at engine damage. The same logic applies here.

I’m Anthony Hamilton, Co-Founder and CEO of THE Water Heater Company, and after years of hands-on experience servicing tankless systems across Southern California — including homes dealing with some of the hardest water in the state — I’ve seen what proper attention to tankless water heater maintenance requirements can do to extend a unit’s life and protect a homeowner’s investment. In this guide, I’ll walk you through exactly what needs to be done, how often, and what you can handle yourself versus when to call a pro.

Understanding Your Tankless Water Heater Maintenance Requirements

To understand why your unit needs attention, we have to look at what’s happening inside those sleek metal covers. Unlike a traditional tank that holds 50 gallons of water, a tankless unit uses a high-powered heat exchanger to flash-heat water as it flows through narrow copper or stainless steel tubes.

In Southern California, our water is naturally high in minerals like calcium and magnesium. When this “hard water” is heated, these minerals crystallize and stick to the walls of the heat exchanger. This is known as scale. Even a tiny layer of scale—as thin as 1/16th of an inch—can reduce the thermal efficiency of your unit by up to 12%.

When scale builds up, it acts as an insulator. Your burner has to stay on longer and burn hotter to get the water to your desired temperature. This doesn’t just spike your energy bills; it physically stresses the metal. Eventually, the heat exchanger can overheat and crack. By staying on top of tankless water heaters maintenance, you ensure that your system hits that 24%–34% energy savings mark and lasts its full 20-year expected lifespan.

Essential Tasks for Your Tankless Upkeep Checklist

Maintaining a tankless system involves more than just the water lines. Because these units are precision-engineered machines, they have several “gatekeepers” that need to be kept clear to ensure safe and efficient combustion.

1. Cleaning the Inlet Water Filter

Most units have a small screen located where the cold water enters the heater. This screen catches pebbles, sediment, and debris from the city water main. If this gets clogged, your water pressure will drop significantly. We recommend checking this every 3 to 6 months. Simply shut off the water, unscrew the filter, rinse it under a tap, and pop it back in.

2. Cleaning the Air Intake Screen

Your water heater needs to “breathe” to burn gas efficiently. An air intake filter prevents dust, lint, and even small insects from entering the burner assembly. If this filter is dirty, the unit may struggle to stay lit or throw an error code. You can usually clean these with a soft brush or a quick rinse with cool water.

3. Flushing the Heat Exchanger (Descaling)

This is the most critical of all tankless water heater maintenance requirements. It involves circulating a food-grade descaling solution (like white vinegar or a specialized citric acid solution) through the unit for about 45 to 90 minutes. This dissolves the calcium deposits and restores full flow and heat transfer. If you notice your shower temperature fluctuating or “sandwiching” (going from hot to cold to hot), it’s likely time for a flush. If the unit is already acting up, you may need professional water heater repair services to clear the blockage.

4. Inspecting the Condensate Trap

If you have a high-efficiency “condensing” model, your unit produces a slightly acidic liquid as a byproduct of heating. This liquid collects in a condensate trap. If the trap or the drain line gets blocked by debris, the liquid can back up into the unit and cause a total system shutdown.

5. Pressure Relief Valve and Venting

Safety first! The pressure relief valve (PRV) should be tested annually to ensure it hasn’t seized up. Additionally, we always check the venting pipes. In Southern California, it’s common for birds or wasps to try and nest in the exhaust vents, which can lead to dangerous carbon monoxide buildup if not cleared.

How Water Hardness Affects Tankless Water Heater Maintenance Requirements

Water hardness is measured in grains per gallon (gpg). In many parts of Southern California, we see “very hard” water, often exceeding 10 or 15 gpg. The harder your water, the faster those minerals precipitate out and form scale.

If you have a water filtration and conditioning system installed, you might only need to flush your unit every 3 to 5 years. Without one, an annual flush is the bare minimum.

Professional vs. DIY: Meeting Your Tankless Water Heater Maintenance Requirements

We often get asked: “Can I do this myself?” The answer is yes—if you are handy and have the right equipment. To DIY a flush, you’ll need a submersible pump, two heavy-duty hoses, a five-gallon bucket, and several gallons of food-grade white vinegar or descaling powder.

However, there are several reasons why homeowners in Santa Barbara, Pasadena, and across Los Angeles prefer to call us for water heater maintenance. A professional service isn’t just a flush; it’s a comprehensive health check.

When we come out, we don’t just run vinegar through the pipes. We:

• Check the gas pressure to ensure the burner is firing correctly.
• Inspect the electrical connections and torque them to factory specs.
• Clean the flame rod and igniter (components that often fail if neglected).
• Verify that the venting is sealed and sloped correctly to prevent leaks.
• Check for tiny leaks that haven’t become “floods” yet.

Protecting Your Investment and Warranty

One of the most overlooked aspects of tankless water heater maintenance requirements is the fine print in your manufacturer’s warranty. Most major brands, including Navien, Noritz, and Rheem, explicitly state that damage caused by scale buildup is not covered under warranty.

Furthermore, many manufacturers require documented proof of annual professional maintenance to keep the heat exchanger warranty valid. If your unit fails in year seven, but you can’t show that it was ever serviced, you might be on the hook for a full water heater replacement.

By keeping a service log and having a factory-certified technician handle the heavy lifting, you aren’t just buying a flush—you’re buying an insurance policy for your home’s hot water. Regular maintenance can extend the life of your unit from 10 years to over 20, effectively doubling the value of your initial investment.

Frequently Asked Questions about Tankless Upkeep

How often should a tankless water heater be flushed?

For most Southern California homes, we recommend an annual flush. However, if you have a large family using a lot of hot water, or if you live in an area with particularly high mineral content (like parts of Santa Clarita or Santa Ana), every 6 months is much safer.

What are the signs that my tankless unit needs immediate service?

Keep an ear and an eye out for these “red flags”:

• Error Codes: If you see numbers flashing on your display (like Code 11 or E003), your unit is telling you something is wrong.
• The “Cold Water Sandwich”: Getting a burst of cold water in the middle of a hot shower.
• Reduced Pressure: If the hot water side of your faucet is noticeably weaker than the cold side.
• Noises: Banging, knocking, or screeching sounds coming from the unit during operation.

Can neglecting maintenance void my manufacturer warranty?

Yes. Almost every manufacturer considers “scale accumulation” a result of poor maintenance rather than a factory defect. If the heat exchanger fails because it’s choked with calcium, the warranty will likely be denied. Always keep your service receipts!

Conclusion

At THE Water Heater Company, we take pride in being Southern California’s go-to experts for all things hot water. Whether you’re in the coastal breeze of Santa Barbara and Camarillo, the valleys of Van Nuys and Santa Clarita, or the busy neighborhoods of Pasadena, Irvine, and Los Angeles, we understand the local water conditions that affect your appliances.

Meeting your tankless water heater maintenance requirements doesn’t have to be a headache. Our family-owned team is dedicated to providing fast, reliable, and expert service that keeps your showers hot and your energy bills low.

Why choose THE Water Heater Company?

• Local Expertise: We know SoCal water and how to beat the scale.
• Specialized Focus: We aren’t general plumbers; we are water heater specialists.
• Transparent Service: We explain exactly what your unit needs and why.
• Warranty Protection: Our professional documentation keeps your manufacturer coverage intact.

Don’t wait for an error code to leave you with a cold shower. Check out our current specials and rebates and schedule your maintenance visit today. Let us help you get the most out of your tankless investment!