How to Remove Air in Hot Water Lines

Published onMay 3, 2024
Appliance Maintenance and Care, How-to Guides, Resources

Air in hot water lines can come from new water heater installations, faulty anode rods or pressure relief valves, or issues with your water supply. To get rid of this air, you’ll need to purge it out of your water pipes and then check these components to make sure they’re working correctly.

If you have noisy pipes, notice your taps are sputtering, or have a significant change in water pressure at your sinks or showerheads, it could be a sign that air is trapped in your hot water lines.

Ignoring this issue can accelerate the oxidation and deterioration of your pipes, causing long-term damage to your plumbing system.

To effectively remove these air pockets, you first need to identify which part of your plumbing system is allowing air to enter the system.

Table of Contents

What Causes Air to Get Into Water Pipes

The most common reasons why air gets into water pipes include:

You just had a new water heater installed
The anode rod in your water heater is producing hydrogen gas
You have a bad water heater pressure relief valve
There’s an issue with your incoming water supply

In the following sections, we’ll discuss each possible source of the problem and guide you through determining whether it’s the reason why you have air in your hot water lines.

Why Air Is Getting Into Your Hot Water Lines After Replacing A Water Heater

If you’ve recently had your water heater replaced, it’s not uncommon to encounter air, dirt, or debris coming out of your hot water line.

The sound of your fixtures spitting out bursts of air bubbles is a typical occurrence if the water lines weren’t bled out enough after the new water heater was installed.

Air can be introduced into a plumbing system anytime a pipe is opened. During your water heater installation, one of the following actions probably took place:

An existing line was opened to change or add a fitting.
An existing line was tapped into in order to add a new water line.
A section of the water line was removed and replaced.

Each of these actions, which are standard when replacing a water heater, will cause air to get trapped inside your water lines.

Once your plumbing system is tied back together and pressurized, this air will sit there until it’s purged out.

How to Remove Air From Hot Water Pipes in Your House

Most of the time, the easiest way to remove or “bleed” the air out of a hot water line is to open up a bathtub faucet and turn it all the way to the hot side.

Let it run for a couple of minutes until the “air burps” stop and you see a clean flow of water.

If you’re doing this right after your water heater was installed, you’ll probably see dirty brown water with some small dirt or debris entering your tub initially.

This is normal. Just keep the tap open until the air is completely purged out and the water is clean.

Don’t open up any sink faucets to purge the air out of your hot water line. The dirt and debris passing through can clog up or break the aerator in your fixture, creating another problem.

This aerator is the mesh piece you see screwed under your faucet spout. The mesh allows air to mix with the water coming out of your faucet to help maintain a steady and splash-free stream.

How Long Does it Take to Get Air Out of Hot Water Lines?

If you’re using a tub faucet, it should only take 2 to 3 minutes to remove all of the air bubbles from your hot water line. This process can take longer on larger homes with more sections of plumbing lines.

If you have multiple tubs, open each one so the air is completely removed from your entire plumbing system.

Regardless of how large your home is, the air should bleed out within 5 to 10 minutes.

What To Do if Air is Still in Your Plumbing Lines After a Few Weeks

If you’re still experiencing air coming out of your faucets after bleeding them out, this could be a sign of another problem.

This could mean:

The anode rod in your water heater is producing hydrogen gas and releasing air bubbles
You have a faulty pressure relief valve on your water heater

Anode Rod

An anode rod is a metal rod placed inside a water heater tank to prevent corrosion. It works by attracting minerals and sediment from the water being held inside the tank.

These anode rods are made up of two parts—a steel wire inside the rod that uses electrolysis to pull in and collect the particles and a metal covering, typically made of magnesium, aluminum, or zinc, that gives the particles a place to land so the anode rod corrodes before the tank does.

Without an anode rod installed, the integrity of the tank would be weakened, and its lifespan would be shortened.

Most manufacturers ship their water heaters out with anode rods wrapped in magnesium. While magnesium works well with softer water, they aren’t the best option for the harder water that would come with a private or community well system.

In locations with high sulfate levels in the water, these magnesium anode rods have been known to create hydrogen sulfide gas, which can lead to hydrogen bubbles within the tank and in your water lines.

So, if your anode rod is made with magnesium, it could be the reason you still have air bubbles coming out of your fixtures. You’ve also probably already noticed a smell or different taste to the water.

Water Heater Pressure Relief Valve (T&P Valve)

A water heater’s pressure relief valve or T&P valve, is designed to relieve air or water when there’s an excess of pressure within a tank or if the water being held inside it is too hot.

You’ll find this relief valve on the side or top of the tank with a discharge pipe connected to it, leading to a drain or outdoors.

If a relief valve on a water heater gets clogged or fails, it can trap air inside the tank and introduce it into your water lines.

This could be the reason you’re still experiencing air bursts when opening up a hot water line after purging your water pipes.

To see if this is the problem, you can test the T&P relief valve.

How to Test a Water Heater T&P Relief Valve

Note: Be careful here—the water coming out of a pressure relief valve will be extremely hot, and if the valve is opened all the way, it can release a lot of hot water.

To do this:

Place a bucket or deep bowl underneath the discharge pipe if indoors.
Gently pull up the lever until you begin to hear air being released. In most cases, you won’t need to pull the lever all the way up.
Once you begin hearing air, hold the lever for another 10 seconds or until you see water coming out of the discharge pipe.

What To Do if You’re On A Private Well and Air is Coming Out of Your Faucets

If you haven’t had a water heater recently installed and you’ve checked your water heater’s anode rod and relief valve but still have air coming out of your faucets, you probably have a problem with your water supply.

If you use city water or are on a community well, contact your water supply company to see if there’s anything they’ve changed on their system or if anyone else is experiencing the same problems.

If you’re on a private well and experience these issues, you’re more than likely getting air in your cold water line as well.

To see if the air is coming from your well system, have a contractor come out to check the following:

The well pump: A bad well pump can pull in air as it cycles, allowing it to enter your plumbing lines.
The water level: If the pump in your well isn’t fully submerged, it will begin to pull in air.
The supply line: Air can get into your house lines from a leak in the underground supply line coming from the well.

If you’ve checked each potential source we covered here and you’re still experiencing air in your water pipes, call in a professional plumber to see if they can find the source.

They will have more tools and equipment to see if something else is causing air to enter your water lines.

Let us know in the comments below if you’ve experienced air in your hot water lines and if the root cause of it was something other than what we mentioned here since this is a problem anyone could encounter one day.