Tankless water heaters have become one of the most popular upgrades for homeowners throughout York, Rock Hill, Fort Mill, Lake Wylie, Clover, Tega Cay, and surrounding areas in the Carolinas. They provide endless hot water, improved energy efficiency, and often last significantly longer than traditional tank-style water heaters.
However, unlike many homeowners assume, tankless water heaters are not maintenance-free.
One of the most important services you can perform is an annual tankless water heater flush.
Without routine flushing and descaling, mineral deposits can build up inside the unit’s heat exchanger, reducing efficiency, restricting water flow, increasing utility costs, and potentially shortening the lifespan of the system.
At Danco Plumbing Services, we recommend having your tankless water heater flushed at least once per year to keep it operating at peak performance.
Watch: How to Perform a Tankless Water Heater Flush
In this video, Danco Plumbing Services walks through the complete tankless water heater flushing process, including safely shutting down the unit, cleaning internal filters, circulating descaling solution, and flushing the system with clean water before returning it to service.
What Is a Tankless Water Heater Flush?
A tankless water heater flush is a preventative maintenance procedure designed to remove scale, sediment, and mineral buildup from inside the heat exchanger and water passages of the unit.
As water passes through the heater, naturally occurring minerals such as calcium and magnesium can accumulate on internal components. This buildup is especially common in homes with hard water.
Over time, these mineral deposits can:
- Reduce heating efficiency
- Restrict water flow
- Cause inconsistent water temperatures
- Increase energy consumption
- Trigger error codes
- Shorten equipment lifespan
- Lead to costly repairs
Routine flushing removes these deposits before they become a problem.
Why Annual Tankless Water Heater Flushing Is Recommended
Most tankless water heater manufacturers recommend a professional flush at least once every year.
Regular maintenance helps protect your investment and ensures the system continues operating as designed.
Improve Energy Efficiency
Scale buildup acts as an insulating layer inside the heat exchanger.
When heat cannot transfer efficiently to the water, the unit must work harder and run longer to produce the same amount of hot water.
A properly maintained system heats water more efficiently and can help reduce utility costs.
Extend the Life of Your Water Heater
Many tankless water heaters can last 20 years or longer when properly maintained.
Routine flushing reduces strain on internal components and helps prevent premature wear that can lead to expensive repairs or replacement.
Prevent Unexpected Breakdowns
Mineral buildup is one of the leading causes of performance issues in tankless water heaters.
Regular flushing helps prevent:
- Reduced hot water output
- Water pressure issues
- Error messages
- Overheating
- Heat exchanger damage
Protect Manufacturer Warranties
Many manufacturers require proof of annual maintenance to maintain warranty coverage.
Skipping recommended service may result in denied warranty claims if problems occur later.
Signs Your Tankless Water Heater May Need Flushing
If your system has not been serviced recently, you may notice several warning signs.
Inconsistent Water Temperature
Hot water may fluctuate unexpectedly or take longer to reach the desired temperature.
Reduced Water Pressure
Mineral deposits can restrict water flow through the heat exchanger and internal plumbing passages.
Higher Utility Bills
A system struggling with scale buildup often consumes more energy to produce hot water.
Error Codes on the Display
Modern tankless units monitor performance and may display maintenance-related warning codes.
Decreased Hot Water Performance
You may notice less consistent hot water delivery throughout the home.
What Happens During a Professional Tankless Water Heater Flush?
Many homeowners are surprised to learn that flushing a tankless water heater involves much more than simply running water through the unit.
A proper service includes several important steps.
1. Safely Powering Down the Unit
Before any maintenance begins, power to the tankless water heater should be turned off and disconnected from the power supply.
The water inlet and hot water supply valves are also shut off to isolate the unit from the home’s plumbing system.
Safety is always the first step.
2. Cleaning the Exhaust Vent Screen
After removing the front panel, the exhaust vent screen should be inspected and cleaned.
Dust and debris can accumulate on the screen over time, potentially restricting airflow and reducing performance.
A quick cleaning helps maintain proper ventilation and efficient operation.
3. Accessing the Service Valves and Relief Ports
Most professionally installed tankless water heaters include a valve kit with dedicated service ports or relief ports on both the hot and cold sides of the system.
These ports allow technicians to connect flushing equipment and circulate cleaning solution through the unit without disconnecting plumbing lines.
4. Removing and Cleaning the Cold Water Inlet Filter
One of the most commonly overlooked maintenance items is the cold-water inlet filter screen.
This small screen often collects sediment, debris, and mineral particles before they enter the heater.
If the screen becomes clogged, water flow can be restricted and overall system performance can suffer.
The filter should be removed, cleaned thoroughly, and reinstalled before the system is returned to service.
5. Connecting the Flush Pump Properly
A submersible circulation pump is connected to the service valves.
For proper circulation, the pump sends cleaning solution into the cold-water service port, while the solution exits through the hot-water service port and returns to the bucket.
This creates a continuous cleaning loop that allows the descaling solution to reach all internal water passages.
6. Circulating Descaling Solution
Once connected, a professional-grade descaling solution is circulated through the tankless water heater.
At Danco Plumbing Services, solutions such as Haymaker Descaler are commonly used to dissolve mineral buildup safely and effectively.
The solution is typically circulated for approximately 30 to 45 minutes, allowing it to break down scale deposits throughout the heat exchanger.
This is the heart of the entire tankless water heater flush process.
7. Flushing the System With Fresh Water
After descaling is complete, the cleaning solution is removed and the system is thoroughly rinsed with fresh water.
Typically, approximately 10 to 15 gallons of clean water are flushed through the hot-water drain valve.
This step is extremely important because you do not want residual descaling solution remaining inside the unit.
The fresh water rinse removes both leftover cleaning solution and loosened mineral deposits before the system returns to normal operation.
8. Restoring the Water Heater to Service
After all maintenance is complete, valves are returned to their normal operating positions, the system is reassembled, and power is restored.
The unit is then tested to verify proper operation and hot water production.
Hard Water Makes Tankless Water Heater Flushing Even More Important
Many homes throughout York County and surrounding areas experience moderate to hard water conditions.
Hard water contains elevated levels of dissolved minerals that accelerate scale formation inside tankless water heaters.
Homeowners in:
- York
- Rock Hill
- Fort Mill
- Tega Cay
- Clover
- Lake Wylie
- And surrounding areas in the Carolinas
often benefit significantly from routine flushing and descaling.
In some cases, adding a water softener or whole-home water filtration system can further reduce mineral buildup and extend equipment life.
Can Homeowners Flush Their Own Tankless Water Heater?
While DIY flush kits are available, the process requires:
- Isolation valves
- Service ports
- A submersible circulation pump
- Descaling solution
- Knowledge of manufacturer procedures
- Safe handling of plumbing and electrical components
Improper maintenance can damage equipment or leave the system inadequately cleaned.
Professional service ensures the process is completed correctly while providing an opportunity to inspect the unit for potential issues before they become expensive repairs.
Why Homeowners Trust Danco Plumbing Services
Danco Plumbing Services proudly serves homeowners throughout York County, SC, and surrounding communities with reliable residential plumbing services.
Our team specializes in:
- Tankless water heater flushing
- Tankless water heater maintenance
- Tankless water heater repair
- Tankless water heater installation
- Traditional water heater services
- Leak detection and repair
- Drain cleaning
- General plumbing repairs
As a locally owned company based in York, SC, we understand the unique plumbing challenges homeowners face throughout our area and are committed to providing honest recommendations and quality workmanship.
Schedule Your Tankless Water Heater Flush Today
If it has been more than a year since your last tankless water heater flush, now is the perfect time to schedule maintenance.
Routine flushing helps improve efficiency, extend equipment life, maintain manufacturer warranties, and reduce the likelihood of unexpected breakdowns.
Danco Plumbing Services
Serving York, Rock Hill, Fort Mill, Tega Cay, Clover, Lake Wylie, Indian Land, and surrounding communities throughout York County, SC and nearby Carolina areas.
