Cold showers that come out of nowhere, rising gas or electric bills, and endless “rebooting” of your tankless unit are all signs that your water heater isn’t just inconvenient – it’s wasting energy and money. Tankless systems are designed to be efficient, but when something goes wrong, that efficiency drops fast. Every bit of scale buildup, every struggling sensor, and every misadjusted gas valve forces your tankless water heater to work harder to deliver the same hot water. That extra strain shows up on your utility bill and shortens the lifespan of a unit that should last you well over a decade.
In Keller, TX, where homes often juggle multiple bathrooms, large families, and high hot water demand, a tankless water heater that’s even slightly out of tune can make a noticeable difference in both comfort and costs. Many homeowners assume that as long as hot water eventually comes out of the tap, the system must be “fine.” But tankless systems are precise appliances; a minor issue that would go unnoticed in a traditional tank can quickly erode efficiency in an on-demand unit. Repairing and optimizing your tankless heater is not just about preventing a breakdown; it’s about restoring the performance and energy savings you paid for in the first place.
All Source Plumbing sees this every week in Keller and the surrounding communities: tankless systems that are only a few years old, but already running at a fraction of their original efficiency because they’ve never been properly serviced or repaired. With the right diagnostics, targeted repairs, and a smart maintenance plan, your tankless water heater can deliver faster hot water, quieter operation, lower energy use, and a longer service life. Understanding how and why to repair for efficiency is the first step.
Why Efficiency Drops Over Time
Tankless water heaters don’t store hot water; they heat water as it flows through the unit. That process depends on a clear pathway for water, clean heat exchangers, accurate sensors, and correctly calibrated gas or electric input. Over time, minerals in Keller’s hard water begin to coat the inside of the heat exchanger. That thin layer of scale acts like insulation, forcing the burner or heating elements to work harder and longer to raise the water temperature. The unit may still reach the set temperature, but it burns more fuel or draws more electricity to get there, quietly eroding your efficiency.
Another common cause of efficiency loss is sensor drift or partial failure. Tankless systems rely on flow sensors, temperature sensors, and exhaust sensors to modulate output. When a sensor becomes dirty, corroded, or worn, the unit can overcompensate or underperform. For example, a misreading temperature sensor might cause the system to heat water hotter than necessary, then mix in more cold water, wasting energy on every shower. These problems rarely cause an immediate total failure, which is why many homeowners don’t notice an issue until the utility bill spikes.
Ventilation and gas supply also play a role. If the venting is partially blocked or improperly sized, or if the gas pressure is slightly off, the burner cannot operate at peak efficiency. The flame may be weaker, incomplete combustion can occur, or the unit may cycle on and off more frequently. All of that translates into more energy consumed for less usable hot water. In Keller’s mix of older and newer homes, it’s not unusual for a tankless replacement to be connected to existing gas lines or vents that aren’t quite ideal, and that mismatch shows up in long-term efficiency unless corrected.
Signs Your Tankless Needs Repair
Efficiency problems often start quietly, but your tankless water heater will usually give you clues that it needs attention before it fails completely. One of the most obvious signs is inconsistent water temperature: hot and cold fluctuations during a shower, or hot water that takes longer than it used to arrive at the tap. This “temperature hunting” often indicates scale buildup on the heat exchanger or issues with the flow sensor, both of which directly impact efficiency and comfort.
Another warning sign is unusual noises. A healthy tankless unit operates with a low, steady sound when running. If you begin to hear rattling, popping, or loud whooshing, it can mean that mineral deposits are interfering with the burner, or that airflow through the vent is restricted. These conditions force the system to work harder and can lead to incomplete combustion, which wastes fuel and stresses internal components. Ignoring these sounds can turn a small, fixable issue into a costly major repair later.
Your utility bills can also be a diagnostic tool. If your gas or electricity usage has climbed without a clear reason – no new appliances, no change in family size – your tankless system could be operating at reduced efficiency. All Source Plumbing technicians in Keller often compare historical usage with the age and maintenance history of the unit to pinpoint whether the tankless heater is likely to be the culprit. Combined with error codes on the unit’s display or frequent resets, rising energy costs are a strong indicator that it’s time for professional repair and efficiency tuning.
Key Repairs That Restore Performance
When a tankless water heater in Keller is underperforming, one of the first repairs All Source Plumbing may recommend is a thorough descaling and flushing of the heat exchanger. Using a pump, hoses, and a cleaning solution designed for tankless units, the technician circulates fluid through the system to dissolve mineral deposits. This process can dramatically improve heat transfer, allowing the burner to achieve the desired temperature with far less energy. Many homeowners are surprised at how much quieter and faster their unit becomes after a proper flush.
Sensor and component replacement is another critical aspect of efficiency-focused repair. Flow sensors, temperature sensors, ignition electrodes, and fans can gradually fail or become inaccurate. Rather than waiting for a total breakdown, a technician can test these parts, compare readings to manufacturer specs, and replace components that are out of range. This restores the unit’s ability to modulate output precisely, which is the key advantage of tankless technology. Accurate sensors mean the system can deliver exactly the right amount of heat for the water demand, with minimal waste.
Gas pressure adjustment and venting corrections are often overlooked but can be among the most impactful repairs. If the gas supply is undersized or pressure is off, the burner cannot reach its designed output, leading to longer run times and less efficient combustion. Similarly, if vent runs are too long, improperly sloped, or partially obstructed, exhaust gases may not clear efficiently, causing the unit to throttle down or short cycle. All Source Plumbing can measure gas pressure, inspect venting routes, and make adjustments or upgrades that bring the entire system into alignment with the manufacturer’s requirements, restoring the efficiency you expected when the unit was installed.
Preventive Maintenance For Lasting Efficiency
Once your tankless water heater has been repaired and tuned for peak efficiency, keeping it that way becomes the next priority. Preventive maintenance is not just a sales pitch; for on-demand systems, it is the difference between a 20-year lifespan and a 7-year headache. In Keller, where water hardness is often moderate to high, annual descaling is usually recommended. This regular flushing prevents thick layers of mineral buildup from ever forming, so the heat exchanger can continue to transfer heat efficiently year after year.
During a maintenance visit, an All Source Plumbing technician does more than just flush the unit. They inspect and clean the inlet screens, check and clean the burner assembly, verify sensor operation, test gas pressure, and confirm that the venting is clear and properly configured. Catching a partially clogged air intake or a failing fan early means the system continues operating at high efficiency instead of slowly declining. This proactive approach is especially valuable in busy Keller households, where the tankless unit may run many hours each day.
Homeowners can also support efficiency between professional visits with a few simple habits. Keeping the area around the unit clear allows for proper airflow and makes it easier to spot leaks or corrosion early. Avoiding extreme temperature settings – for example, setting the unit to 120°F instead of 140°F unless absolutely necessary – reduces energy use and scale formation. Monitoring how long it takes hot water to arrive and whether any new noises or error codes appear gives you an early warning system. When something feels “off,” scheduling a service call before the issue worsens can save both energy and repair costs.
Repair Versus Replacement Decisions
At some point, every homeowner with a tankless water heater faces the question: is another repair worth it, or is it time to replace the unit entirely? From an efficiency standpoint, this is a crucial decision. Older tankless models may have lower baseline efficiency than newer units, and repeated breakdowns can signal internal wear that no longer makes economic sense to fix. All Source Plumbing evaluates not only the immediate problem but also the age, condition, and efficiency rating of your current unit to help you make a smart choice.
If your tankless heater is relatively young, well under its expected service life, and has not had major issues before, targeted repairs and maintenance almost always deliver the best value. Restoring a few worn components and eliminating scale can return the system close to its original efficiency at a fraction of the cost of replacement. On the other hand, if your unit is over 12–15 years old, has frequent error codes, or has significant corrosion or internal damage, a new high-efficiency model may offer better long-term savings, especially with modern advances in burner technology and controls.
In Keller, TX, replacement can also be an opportunity to correct installation issues from a previous job: undersized gas lines, improper vent routing, or a unit that was never properly matched to the home’s hot water demand. By starting fresh with a correctly sized, professionally installed system, you can lock in higher efficiency from day one. All Source Plumbing can walk you through energy usage comparisons, projected utility savings, and available options so you can decide whether to invest in repair, replacement, or a phased plan that balances budget and performance.
Choosing The Right Local Partner
Tankless water heaters are more complex than traditional tank systems, and not every plumber is equally experienced with their diagnostics and repair. Choosing a local partner in Keller who understands both the technology and the local water and gas conditions is essential if your goal is maximum efficiency. All Source Plumbing brings hands-on experience with a wide range of brands and models, as well as familiarity with the specific mineral content of Keller’s water and common installation practices in area homes.
When evaluating who to trust with your tankless repair, ask about their process. An efficiency-focused plumber will talk about descaling, sensor testing, combustion analysis, and gas pressure verification, not just “resetting” the unit or clearing an error code. They will also be comfortable explaining how each repair step affects both performance and energy use. Transparent communication is important; you should understand what’s being done, why it matters, and how it will help your system run more efficiently.
Finally, consider the long-term relationship. Tankless water heaters perform best when they are maintained consistently by someone who knows their history. Working with a Keller-based company like All Source Plumbing means your service records, previous findings, and any unique quirks of your system are all known and documented. That continuity allows for smarter, faster troubleshooting, better efficiency tuning, and fewer surprises over the life of your tankless unit. If you’re also planning other plumbing upgrades, such as Plumbing drain installation, coordinating these projects with the same trusted team can further improve your home’s overall plumbing performance.
Frequently Asked Questions
How often should my tankless water heater be serviced for best efficiency? In most Keller, TX homes, annual service is recommended for optimal efficiency, especially if you have hard water. This typically includes descaling the heat exchanger, cleaning filters and screens, checking burners and fans, testing sensors, and verifying gas pressure and venting. In homes with extremely high usage or very hard water, servicing every 6–9 months may be beneficial. Regular maintenance prevents minor issues from turning into efficiency-robbing problems and helps your unit maintain its original performance.
Can I flush and descale my tankless water heater myself? Some homeowners do perform basic flushing themselves using a pump, hoses, and descaling solution. However, DIY flushing often addresses only part of the efficiency picture. Professional service from All Source Plumbing includes not just descaling, but also inspection and testing of critical components, adjustments to gas pressure if needed, and checks for safety or venting issues. If you’re comfortable with DIY, you can certainly help between professional visits, but relying solely on self-flushing may leave hidden problems unresolved and allow efficiency to decline.
Why is my tankless water heater using more energy even though it still heats water? Increased energy use with “normal” hot water output usually means your unit is working harder than it should. Common causes include mineral buildup on the heat exchanger, dirty or failing sensors leading to inaccurate temperature control, improper gas pressure, or partial vent obstructions. The system may be compensating for these issues by running longer or at higher output. A professional efficiency-focused repair can identify the exact cause and restore proper operation, bringing your energy usage back in line.
Are tankless water heater repairs expensive compared to replacement? The cost depends on the specific issue, but many efficiency-related repairs, such as descaling, sensor replacement, or gas adjustment, are relatively modest compared to a full replacement. For units that are not near the end of their lifespan, these repairs can significantly extend service life and improve energy performance, often paying for themselves over time through lower utility bills. When a unit is very old or has severe internal damage, your plumber may recommend replacement instead, but that recommendation should come after a clear assessment of repair versus replacement costs and benefits.
What can I do day-to-day to help my tankless unit stay efficient? Simple daily habits can make a real difference. Keep the space around the unit clear for good airflow and easy inspection. Set the temperature to a reasonable level, typically around 120°F, to reduce energy use and scale formation. Pay attention to changes in hot water delivery time, water temperature stability, and any new noises or error codes; address these early with a service call. Finally, stick to a regular maintenance schedule with a trusted local company like All Source Plumbing so your system is checked and tuned before small issues can erode efficiency.