Tankless water heaters don’t store hot water like traditional tanks. They heat water only when you need it. That saves space, lowers energy use, and keeps hot water coming as long as the tap stays on.
But to keep all that working smoothly, tankless water heaters need maintenance. Flushing removes mineral buildup that can slow them down or wear them out early.
This guide explains how to flush a tankless water heater, what tools you need, and how often to do it. We also show you signs it might be time to flush and offer pro tips if you’re in an area with hard water.
Key Takeaways
- Flushing removes sediment and scale buildup.
- It helps your system run efficiently and last longer.
- Aim to flush once or twice a year.
- You’ll need vinegar, a pump, and hoses.
- Gas and electric models follow different steps.
- Apollo Plumbing offers expert help if you’d rather not do it yourself.
Why You Should Flush Your Tankless Water Heater
If you have hard water, minerals like calcium and magnesium can collect inside your heater. Over time, this slows performance and raises energy costs. Flushing clears out that buildup.
It also protects heat exchangers and internal parts from wear. Some manufacturers may void your warranty if you skip regular maintenance, so flushing isn’t just helpful—it’s required.
How Often Should You Flush a Tankless Water Heater?
Flush your system once a year. If your water is hard or untreated, do it every six months.
Watch for signs like weaker water pressure, higher energy bills, or strange noises. These could mean scale buildup is already affecting your unit.
Helpful extras:
- Sediment traps: Block debris before it enters the system.
- Water softeners: Cut down on scale-forming minerals.
Tools Required to Flush a Tankless Water Heater
Before you begin, gather what you’ll need.
These tools make the process smoother and more effective:
- Submersible pump
- 5-gallon bucket
- Food-grade white vinegar
- Tankless flushing kit (optional, but helpful)
- Hoses and descaler solution
Step-by-Step Guide: Flushing a Gas Tankless Water Heater
Start by shutting down the system. This keeps it safe to open and flush.
Preparation:
- Turn off power and gas supply.
- Remove the front panel.
- Close the cold and hot water valves.
- Open the pressure relief valve.
- Attach hoses to service ports.
- Set up the pump and bucket with vinegar.
Flushing:
- Pump vinegar through the system for 1 hour.
- Discard used vinegar and flush system with clean water.
- Rinse and clean inlet filters.
Cleanup and Restart:
- Reattach filters and cover panel.
- Open shutoff valves.
- Turn gas and power back on.
Step-by-Step Guide: Flushing an Electric Tankless Water Heater
Electric models don’t use gas, but they still build up scale. Here’s how to clean them out.
Preparation:
- Turn off power at the breaker.
- Open faucets to drain water.
- Remove the cover and take out the heating element.
- Inspect the element for corrosion or scale.
Flushing:
- Fill the unit with vinegar and let it sit for 2 hours.
- Drain and discard the vinegar.
- Reinstall the heating element.
- Run cold water to rinse the system.
Cleanup and Restart:
- Clean the cold water inlet filter.
- Reinstall the panel and restore power.
Trust Apollo Plumbing With Tankless Water Heater Flushing
Regular flushing keeps your tankless water heater running clean and cost-effective. You’ll get better performance and avoid surprise repairs.
If you live in Everett, WA or nearby, call Apollo Plumbing. Our Ready Right Now Plumbers can flush your system, inspect parts, and keep your hot water flowing without hassle.
FAQs
Flushing a tankless water heater may sound like a big job, but it’s a doable task for most homeowners. Here are answers to some of the most common questions.
How long does it take to flush a tankless water heater?
About 1-2 hours from start to finish.
What happens if I don’t flush it?
Minerals collect inside and slow down water flow. Over time, parts can wear out faster and raise energy use.
Can I use something other than vinegar?
Yes. There are descaling solutions made for tankless units, but vinegar is cheap and safe.
Do I need to hire a plumber?
Not always. But if you’re unsure, Apollo Plumbing can handle it fast and safely.
Final Thoughts
Flushing a tankless water heater protects your investment and keeps your water hot when you need it. It doesn’t take long and doesn’t require special skills.
But if you’d rather leave it to a pro, Apollo Plumbing’s Ready Right Now Plumbers are ready when you are.