How To Flush A Navien Tankless Water Heater: A Pro’S Step-By-Step DIY
Ever turn on the shower, expecting that rush of perfectly hot water, only to get a lukewarm, low-pressure trickle? It’s a frustrating start to any day. That drop in performance is often the first sign your hardworking Navien tankless water heater is crying out for a little TLC.
Here at HVACRLY, we know that the idea of servicing an appliance can feel intimidating. But we promise you this: with a few common tools and our expert guidance, you absolutely have the skills to tackle this essential maintenance task. Flushing your water heater isn’t just about fixing a problem; it’s about preventing bigger, more expensive ones down the road.
This comprehensive how to flush a navien tankless water heater guide will walk you through every single step. We’ll cover why it’s so critical, what you’ll need, the exact flushing process, and some pro tips to make sure you get it right the first time. Let’s restore your unit to peak performance and keep that glorious hot water flowing.
Why Flushing Your Navien is a Non-Negotiable Task
Think of your Navien tankless heater like the arteries of your home’s hot water system. Over time, minerals naturally present in your water—primarily calcium and magnesium—build up inside the unit’s intricate heat exchanger. This buildup is called “scale.”
At first, it’s a thin layer. But month after month, it gets thicker, acting like a layer of insulation. This forces your heater to work much harder to heat the water, leading to a whole host of issues:
- Reduced Efficiency: The unit burns more gas or uses more electricity to achieve the same temperature, which means higher utility bills for you.
- Lower Water Pressure: Scale can physically clog the narrow passageways inside the heat exchanger, restricting flow and leading to weak showers.
- Inconsistent Temperatures: The heater struggles to maintain a steady temperature, causing annoying fluctuations between hot and cold.
- Error Codes: A Navien unit will often display an error code (like the dreaded E012 for lime scale detection) when buildup becomes severe.
- Premature Failure: The single biggest threat is permanent damage. Overheating caused by scale buildup can stress components, leading to costly repairs or even a complete unit replacement years before its time.
The benefits of how to flush a navien tankless water heater are clear: you restore efficiency, save money, and dramatically extend the life of your investment. This simple annual task is the cornerstone of any sustainable and eco-friendly how to flush a navien tankless water heater maintenance plan.
Gathering Your Tools and Supplies: A Pro’s Checklist
Before we get started, let’s make sure you have everything you need. Having your tools laid out and ready will make the process smooth and stress-free. You don’t need a truck full of professional gear for this job.
Here’s your essential toolkit:
- A Submersible Pump: A small utility pump, often called a transfer pump, is perfect. Look for one with at least 1/6 HP to ensure it has enough power to circulate the cleaning solution effectively.
- A 5-Gallon Bucket: This will hold your cleaning solution and serve as your circulation reservoir.
- Two Hoses: A pair of standard washing machine hoses (3-4 feet long) are ideal. They have the right fittings and are designed to handle water pressure.
- Descaling Solution: You have two main options here. For warranty compliance and guaranteed results, we recommend a Navien-approved descaler like Nu-Calgon’s Haymaker. However, for a readily available DIY option, 2-3 gallons of plain white vinegar works well. We’ll discuss this more in our best practices section.
- Channel-Lock Pliers or an Adjustable Wrench: You may not need these if your hose connections are hand-tight, but it’s good to have them just in case.
- Old Towels: A little water will inevitably spill. Be prepared by placing towels under the unit before you begin.
The Complete Guide on How to Flush a Navien Tankless Water Heater
Alright, you’ve got your tools and you’re ready to go. We’re going to break this down into simple, manageable steps. Just follow along, and don’t rush. This is one of the most important how to flush a navien tankless water heater tips we can give you: patience is key.
Step 1: Safety First! Power Down and Isolate the Unit
Before you touch a single valve, you must ensure the unit is completely safe. This is the most critical step.
Turn Off the Power: Most Navien units plug into a standard wall outlet. Simply unplug it. If yours is hardwired, go to your home’s electrical panel and flip the breaker that controls the water heater to the OFF position.
Turn Off the Gas: Locate the gas shut-off valve on the pipe leading to your water heater. The handle should be parallel with the pipe when it’s open. Turn it 90 degrees so it’s perpendicular to the pipe. This shuts off the gas supply.
Close the Water Valves: Your Navien has three valves on the bottom: a cold inlet (blue), a hot outlet (red), and the main gas line. Turn the handles on both the hot and cold water lines so they are perpendicular to the pipes, shutting off water flow to and from the unit.
Step 2: Connecting Your Flushing Kit
Now we’ll connect our hoses to the service ports. These ports allow us to create a closed loop for cleaning without affecting the rest of your home’s plumbing.
On your hot and cold valves, you’ll see small T-shaped handles. These are the service port valves. Use pliers to turn both of these handles so they are facing outwards, opening the service ports.
Next, carefully unscrew the caps on the service ports. Attach one of your hoses to the cold water service port (the blue side) and the other hose to the hot water service port (the red side). Make sure they are snug, but don’t overtighten.
Step 3: Preparing and Circulating the Descaling Solution
Place your 5-gallon bucket directly under the unit. If you’re using vinegar, pour 1.5 gallons of vinegar and 1.5 gallons of water into the bucket. If using a concentrated descaler, follow the manufacturer’s dilution instructions.
Place your submersible pump into the bottom of the bucket. Connect the hose coming from the cold water (blue) service port to the outlet on your pump.
Take the other hose, the one connected to the hot water (red) service port, and place the open end securely inside the bucket. You have now created a loop: the pump will push the solution into the cold port, through the heat exchanger, and out the hot port back into the bucket.
Step 4: The Flushing Process
It’s time for the magic. Plug in your submersible pump. You should see the solution begin to circulate immediately, flowing out of the hot water hose and back into the bucket.
Let the pump run continuously for at least 45 to 60 minutes. During this time, the acidic solution is working to dissolve all the mineral scale inside your heater. You’ll likely see the water in the bucket become cloudy, discolored, or even have small flakes in it—that’s a good sign! It means the flush is working.
Step 5: Rinsing the System and Restoring Service
After an hour, unplug the pump. Dump the dirty solution out of the bucket. Now, we need to flush all the acidic cleaner out of the unit with fresh water.
Leave the hot water (red) hose in the bucket. Disconnect the cold water (blue) hose from the pump. Keep the cold hose pointed away from anything sensitive.
Close the cold water service port (the little T-handle). Now, slowly open the main cold water valve that supplies the unit. Fresh water will now flow through the heater, pushing out any remaining solution through the hot water hose and into your bucket. Let this run for a solid 5-10 minutes until the water runs completely clear.
Pro Tip: While the unit is flushing, this is the perfect time to clean the small filter screen on the cold water inlet. Turn the main water valve back off, unscrew the cold water line, and you’ll find a small screen. Gently remove it, rinse it clean of any debris, and put it back.
Step 6: Putting Everything Back to Normal
You’re on the home stretch! Once the unit is thoroughly rinsed, shut the main cold water valve again.
Close both the hot and cold service ports (T-handles). Remove your hoses and screw the service port caps back on.
Now, slowly turn the main cold and hot water valve handles back to their original, parallel positions. Open a hot water faucet somewhere in your house (like a bathtub) to help purge any air from the lines.
Finally, restore the gas supply by turning the valve handle parallel to the pipe, and plug the unit back in or flip the breaker on. Your Navien will power up, and you’re back in business!
Common Problems With How to Flush a Navien Tankless Water Heater
Even with the best guide, you can run into a snag. Don’t worry—most issues are simple fixes. Here are a few common problems and how to solve them.
What if the water doesn’t circulate?
If you plug in the pump and nothing happens, check the basics first. Is the pump fully submerged? Is it plugged into a working outlet? Check your hoses for any kinks that might be blocking flow. Lastly, double-check that you opened the service port T-handles correctly.
I’m getting an error code after flushing.
The most common cause for an error code immediately after a flush is air trapped in the system. Go to the farthest hot water tap in your house and let it run for several minutes to ensure all air is purged. If the error persists, power the unit off and on again to reset it.
There’s a small leak at the service ports.
A drip from your hose connection is usually due to a worn-out rubber gasket inside the hose fitting or from over-tightening, which can damage the gasket. Try reseating the hose. If it still drips, you may need a new set of washer hoses for next time.
Best Practices for a Long and Healthy Navien Life
Knowing how to flush your unit is great, but knowing how to care for it year-round is even better. This is your essential how to flush a navien tankless water heater care guide.
Flushing Frequency: For most homes with moderately hard water, flushing once a year is perfect. If you know you have very hard water (your local municipality can tell you), flushing every 6 to 9 months is one of the best how to flush a navien tankless water heater best practices you can adopt.
Solution Choice: As mentioned, Navien-approved descalers are the “by the book” choice. However, millions of successful flushes have been done with simple white vinegar. It’s effective, cheap, and non-toxic. The choice is yours, but be aware of your warranty terms.
Don’t Forget the Filter: We can’t stress this enough. Cleaning that small inlet water filter every time you flush is crucial. It catches sediment before it can even enter the heat exchanger, providing an extra layer of protection.
Frequently Asked Questions About Flushing a Navien Tankless Water Heater
How often should I really flush my Navien?
The official recommendation is at least once a year. However, this depends entirely on your water quality. If your water is very hard (high in mineral content), you should flush it every six months to prevent severe buildup. If you have a water softener, you might be able to go up to 18 months.
Can I use CLR or another chemical to flush my water heater?
We strongly advise against it. Harsh chemicals like CLR can be too aggressive for the sensitive components and seals inside your Navien’s heat exchanger, potentially causing permanent damage and voiding your warranty. Stick to either a manufacturer-approved, food-grade descaler or plain white vinegar.
What happens if I never flush my tankless water heater?
Ignoring this maintenance will inevitably lead to problems. You’ll experience a gradual decline in performance, higher energy bills, and eventually, a system failure. The cost of replacing a heat exchanger or the entire unit is thousands of dollars, whereas the cost of a DIY flush is less than twenty.
How much does it cost to have a professional flush my Navien?
Hiring a licensed plumber or HVAC technician to perform a tankless water heater flush typically costs between $175 and $300. While it’s a very manageable DIY job, there’s no shame in calling a pro if you’re not comfortable doing it yourself. The cost is a worthwhile investment in your home’s comfort and your equipment’s longevity.
And there you have it! By investing just one hour a year, you protect your Navien water heater, lower your energy bills, and ensure your home has a reliable supply of endless hot water. You’ve taken a huge step in becoming a more empowered and knowledgeable homeowner.
You’ve got this. Stay safe and stay comfortable!
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