Ken's Plumbing | Blog

Installing a tankless water heater is a smart investment. It offers multiple benefits, such as space-saving, reduced energy costs, and increased lifespan, especially when compared to conventional water heaters. 

But like any other plumbing system, enjoying these advantages requires regular maintenance. Without it, minerals may build up inside your water heater, ultimately reducing energy efficiency, shortening its lifespan, leading to clogs in the heat exchanger, and costing more over time. 

One easy maintenance task is flushing your water heater. In this article, we’ll cover some essential information to set you up for the task:

• How often do tankless water heaters need to be flushed
• The signs that indicate your system needs flushing
• The consequences of skipping regular flushes
• Whether tankless water heaters can be flushed by homeowners
• A step-by-step guide to flushing your tankless water heater yourself

How Often Do Tankless Water Heaters Need to Be Flushed?

Most manufacturers recommend flushing your tankless water heater once a year to keep your system running smoothly. This helps to:

• Stop mineral buildup
• Prevent clogs in the heat exchanger 
• Ensuring a long life span for your water heater. 

Some manufacturers may even require this yearly flush to keep your system’s warranty valid. 

If your home has hard water, minerals such as calcium and magnesium may accumulate faster in your system, leading to decreased performance of your tankless water heater. If this is the case, professionals typically recommend flushing the system every six to nine months. 

Signs Your Tankless Water Heater Needs to Be Flushed 

Even with regular maintenance, your tankless water heater may show early indications that it needs attention. Keep an eye out for these warning signs: 

• Fluctuating Water Temperatures: Mineral buildup in your water heater can clog the heat exchanger, leading to inconsistent water temperatures. 
• Reduced Water Pressure: Residue may also clog the pipes, leading to lower water pressure throughout your home.
• Strange Noises: As minerals accumulate in your system, it may lead to unusual noises such as crackling or banging coming from your pipes.   
• Cloudy or Discolored Water: Sediment in your tankless heater can cause your water to appear murky or discolored. 

What Happens If I Don’t Flush My Water Tankless Heater? 

Skipping annual maintenance might not cause immediate trouble, but over time it can lead to serious, long-term problems for both your water heater and your home’s plumbing: 

• Reduced Efficiency and Hot Water Output: Minerals build up inside the heat exchanger, reducing the amount of usable hot water and forcing the unit to work harder, which increases energy consumption and system wear.
• Sediment Spreading through Your Plumbing: If not addressed, mineral deposits can infiltrate into your home’s pipes and fixtures. This can affect water flow, reduce water quality, and interfere with everyday tasks like showering, washing dishes, and doing laundry.
• Risk of Damage and Costly Repairs: Excessive buildup over time can strain the system, leading to breakdowns, a shorter lifespan, and expensive repairs.

Can I Flush My Tankless Water Heater Myself?

Many homeowners may choose to flush their tankless water heater themselves by following the manufacturer’s instructions.

However, if you don’t feel comfortable or equipped to flush your system, hiring a professional plumber ensures safe and proper maintenance, keeping your water heater running smoothly. 

Steps to Flushing a Tankless Water Heater Yourself 

Whether you’re performing the annual flush or tackling a sudden issue, there are two common DIY methods for flushing a tankless water heater. The “right” method depends on the equipment you have and how hands-on you want the process to be.

Method 1: Flushing with a Circulation Pump

Equipment needed: Submersible circulation pump, two hoses, 5-gallon bucket, 1–2 gallons of vinegar.

1. Turn Off Valves and Gas: Shut off your water heater’s power, gas, and the hot/cold isolation valves. The valves should be perpendicular to the pipes when fully closed.
2. Connect the Hoses: Remove the purge port caps on the hot and cold valves. Attach a hose to each valve and tighten the connections to prevent leaks.
3. Set Up the Pump System: Place the pump in the bucket. Connect the free end of the cold-water hose to the pump, and place the hot-side hose into the bucket so water can return.
4. Add the Vinegar: Pour undiluted white vinegar into the bucket until the pump is covered.
5. Run the Pump: Open the service valves and turn on the pump to circulate for 45–60 minutes.
6. Rinse the System: Turn off the pump and dispose of the vinegar. Refill the bucket with clean water and run the pump again for 5-10 minutes to rinse. 
7. Disconnect and Reopen: Close the service valves, disconnect the hoses, reopen the hot and cold water valves, and restore power/gas.
   
   

Method 2: Flushing without a Circulation Pump

Equipment needed: Funnel, two hoses, 5-gallon bucket, 1–2 gallons of vinegar.

1. Turn Off Valves and Gas: Shut off your water heater’s power, gas, and the hot/cold isolation valves. The valves should be perpendicular to the pipes when fully closed.
2. Connect the Hoses: Remove the purge port caps on the hot and cold valves. Attach a hose to each valve and place the end of the hot-side hose into a bucket.
3. Add Vinegar: Open both service valves. Using a funnel, slowly pour undiluted vinegar into the cold-side hose. It will flow through the unit and drain out of the hot-side hose into the bucket.
4. Wait: Let the vinegar sit inside the unit for 60 minutes to break down mineral buildup without active circulation.
5. Rinse the System: Disconnect the cold-side hose. Briefly open the cold water inlet valve to flush the unit until the water coming from the hot-side hose runs clear.
6. Disconnect and Reopen: Close the service valves, disconnect the hoses, reopen the hot and cold water valves, and restore power/gas.
   
   

Need Help Flushing Your Tankless Water Heater? Ken’s Has You Covered. 

Whether you need help installing a new, replacing an old, repairing, or flushing your tankless water, our team is here to help. Ken’s Plumbing offers expert tankless water heater services 24 hours a day, 7 days a week. 

Keep your hot water flowing smoothly. Schedule a service today, contact us online, or give us a call at (864) 661-4890.