5 Ways to Get the Air out of the Hot Water System

Interior of boiler room

Hot water lines are the root of some of the most annoying plumbing problems by far. They cause the water to have a weird flow and color. Also, even though they can’t cause a lot of damage quickly, you should still fix them as soon as possible. Lucky for you, the problem is incredibly easy to spot and solve — if you have the right information.

In this article, we’ll talk about the best 5 ways to get the air out of the hot water system. But first, let’s talk about what causes the air to get trapped in the water lines.

What Causes Air in Water Lines?


Tap, hot and steam

Unfortunately, it’s not always easy to determine what’s causing the issue. However, you can categorize the potential culprits into two categories — the ones that affect solely the hot water or both the hot and cold supply. Before we go to this article we want to let you know that we have written a buying guide on the best tankless water heater reviews that will help you to choose whats the right system for your home needs. Let’s go through some more common scenarios to find out what’s causing the issue.

Trapped air in gravity-fed systems

If your water supply is gravity-fed, the air could get trapped in the supply when it’s cut off for maintenance. If that’s the case, you’re in luck, because that is one of the easiest problems you could have. You can solve it by simply running your taps for some time and letting the air flow out.

Trapped air in well-fed systems

When the water supply is well-fed, it can cause air to appear in your water lines. This scenario could happen for one of three reasons.

First, it could signify a faulty check valve, which lets contaminants get into your water supply and can be potentially dangerous.

Second, it could mean that there’s methane seeping into your water supply through the pipes. Although the gas is flammable, it’s technically harmless to the water supply — but you should fix it nevertheless.

Lastly, the feed line sometimes can’t protrude into the well water as far as it needs. Thus, it will start allowing air to enter the line and cause more issues.

Air trapped in hot water systems

If you don’t purge your heater often, sediment can build up and cause the air to get trapped. Sediment build-up commonly occurs in well-fed systems, but fortunately, there’s an easy way to fix it. By cleaning the system, you will allow the trapped air to escape, and fix your system within a few hours.

Now that you know how air ends up in your water systems, let’s see how you can fix the problem.


5 Ways to Get Air out of the Hot Water System

Method 1

Begin by shutting the power off and leave the cold water on to let the tank cool for approximately 30 minutes. If your water system is gas-run, you’ll need to turn off the switch close to the bottom of your tank. However, if you have an electric tank, you’ll have to shut it off the circuit breaker.

Lay a plastic tarp under your drain tap and attach a hose line that will carry all of the runoff into the sewer. Open the drain valve to empty the tank. That will force all trapped air or sediment out. When the water starts running clean again, it means you’ve drained the tank and you can close the drain valve to allow the tank to fill up again. Lastly, you can restore the power once the tank is full and enjoy your fresh air-free water supply.

Method 2

Believe it or not, you can even use your washing machine to get rid of excess air in the hot water system. Disconnect the hot (red) water pipe and connect the cold (blue) pipe in the red one’s place. Open the hot water and the cold water tap and let them run for 3–5 seconds. Repeat the process if the problem persists.

Method 3

First, make sure you’ve turned off the main water line so you don’t make a mess while you’re trying to fix the problem. If your home has several floors, start at the top one, or at the fixture adjacent to the place where the water supply enters the home.

Open each faucet and let the water run to allow the air to escape. Once the air starts flowing normally, you can turn off all of the fixtures and turn the water line back on.

Method 4

Make sure your water valve is connected to the boiler to ensure the water is available. Open all of the valves that go to different heating zones in your home, and close all of the shutoff valves.

Locate one of the spigots that come off the return line and attach a garden hose to it. Open the self-feeding valve and the spigot so you can drain the water into a drain or bucket. However, be careful as the water will be incredibly hot. Lastly, let the water run out of the hose until you can’t see any air bubbles.

Method 5

Unfortunately, sometimes you can’t get the air out of a hot water system, and you’ll need to replace the piping. If you’ve tried all of the methods above, and not one seems to work, it could be a sign that the valves are blocked. More often than not, it happens because the pipes or appliances in your home aren’t set up properly. If that’s your case, you’ll probably need to hire a mechanic and have them inspect and fix the problem.

So, now that you know what causes excess air in hot water lines, and how to fix it, let’s talk about the easiest ways to spot it.


Top 4 Signs of Air in Hot Water Lines

As I said, it’s usually quite noticeable when there’s air running in your hot water lines. The easiest way to find out if there’s excess air is if you live in a home that has steam registers. In that case, your pipes will start making a pinging noise that’s impossible to ignore.

Another common telltale sign is the water not flowing but out the faucet. Additionally, if your pipes start to vibrate at lower pressures — the water flow is probably completely off. Lastly, if the water looks cloudy or almost milky, it could signify that there’s some trapped air in your hot water lines.


Final Thoughts

Air in the hot water lines is one of the most common issues professional plumbers come across. However, as you can tell, there are multiple tricks you can do without having to hire anyone to fix it. I hope this article helps you get the air out of your hot water systems quickly and easily.

Related Topic: 5 Ways to Clean Sediment from an Electric Water Heater

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