Why Is Gas Water Heater Humming?

A gas water heater can be making all sorts of noises, but not all of them are harmless.

Your unit might start humming, in case a part of the burner is malfunctioning – the component has metal elements that can start rubbing against each other. An issue with the gas supply, the flex adapter, and the shut-off valve can also make a gas water heater hum.

Do Gas Water Heaters Make Noise?

All in all, gas water heaters are a bit noisier than electric units, but the sounds shouldn’t be disturbing in any way.

Under normal circumstances, you may hear the water heater fire up and the water start moving around the system. It is also absolutely normal to notice a gurgle or a tick from time to time.

Ideally, you would want to remember how your water heater should sound, and if you ever hear something that is not ‘normal’, you should immediately start looking for the cause.

Read: Why Gas Hot Water Heater Is Not Heating? – Troubleshooting Guide

Why Would a Water Heater Hum?

The great news is that, in general, a humming noise does not indicate a serious issue with your water heater.

When it comes to electric units, the chances are high that one of the heating elements has become loose. All you would have to do to stop the vibration (and the consequent humming) is tighten the component.

Why Is Gas Water Heater Humming?

Humming noise in a gas water heater usually means that the burner, or a part of it, is defective.

This compartment has metal plates that can get worn out over time. When this happens, the metal elements will start rubbing against each other, creating a humming sound.

Such a noise might also mean that there is a problem with…

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  • The gas supply
  • The flex adapter
  • The gas burner assembly
  • The shut-off valve
  • Not enough clearance

Read: Gas Water Heater Thermocouple Possible Issues

Tankless Hot Water Heater Making Humming Noise

If you can hear your tankless water heater produce a noise even when you are not using any hot water, then the chances are high that there is a vacuum siphoning water away from the heater which is causing the vibration and humming.

A defective pressure valve, blocked ventilation, and a dirty flow sensor can also make your tankless unit produce different noises.

How Do You Fix a Humming Gas Water Heater?

  1. First things first, you would have to make sure that there is enough free space around the water heater. If other objects are touching the unit, they might start producing a humming noise, while the water heater is operating.
  2. After that, you can check the gas supply line. Make sure that it is properly fitted and that there are no kinks.
  3. If your system has a flex adapter, check this component as well. An improperly fitted flex adapter can make a humming noise when the pressure in the system drops (that happens when the water heater is turned on).
  4. Locate the shut-off valve and confirm that it is fully open. A closed or partially closed valve would restrict the flow of water and this will make the unit hum once it’s on.
  5. Finally, check the burner assembly. A malfunctioning component would have to be replaced, but you might want to leave that to a professional.

Is It Normal to Hear Water Heater Noise?

Water heaters would be making some noises while operating, but they shouldn’t be disturbing in any way.

A hybrid water heater, for example, has a noise level between 40 and 80 decibels. For comparison, the telephone dial tone is 80 decibels.

With that being said, there are certain sounds that your unit should not be making under normal circumstances.

Here are the most common sounds that you should be aware of:

  • Banging and rumbling (usually indicate that there is a lot of sediment build-up in the tank)
  • Crackling and hissing (might sometimes be heard in a normally operating electric unit, but in a gas-fired appliance may indicate a condensation problem)
  • Screeching and whistling (high-pitched sounds might mean that one of the valves has gone loose)
  • Popping (this sound is, once again, associated with sediment build-up)

Read: Why Water Heater Is Leaking?

Why Is My Gas Water Heater Buzzing?

In general, a buzzing sound can be an indication of the same issues as a humming noise.

In an electric water heater, it, most likely, means that the heating element is loose and the water flowing around this component is making such a noise.

In gas water heaters, the most common reason for a buzzing noise is an issue with the burner.

Why Is My Hot Water Heater Howling?

A howling sound generally indicates that there is a pressure issue in the system or a problem with the gas or water flow.

For example, your gas line cut-off valve may not be completely open.

Another thing that you might want to check is the house’s plumbing. Trapped air and too much pressure in the plumbing lines can be causing the howling.

In such a case, you might have to adjust the pressure regulator that is usually located outside the house.

Hot Water Heater Vibrating House

The vibration might be caused by a loose heating element or a malfunctioning burner.

Another thing that you can check is the shut-off valve (there might be one right under your sink). In case it is partially closed, the valve would obstruct the water flow and make this part of the system vibrate.

Hot Water Tank Sounds Like a Kettle

The sound of water boiling in your water heater like in a kettle actually has a special term which is ‘kettling’. 

The most common cause of such a sound is the bubbles that are trying to make their way through a layer of sediment

This build-up usually develops at the bottom of the tank, right where the heat is introduced to the unit. So, the layer of trapped water between the tank and the sediment will heat up and try to ‘bubble’ its way through the minerals.

Another possible cause of ‘kettling’ is overheating. The issue might be not as serious as it sounds, and all you would have to do is adjust the thermostat, but if that didn’t help, then calling a professional plumber is the right thing to do. 

Read: Is Furnace And Water Heater The Same?

Why Is My Hot Water Heater Making Knocking Sounds?

There is practically no doubt that if your water heater is making a knocking sound it has a layer of sediment at the bottom of the tank.

The water that gets heated up will eventually break up the sediment into smaller parts and these minerals will produce the knocking sound inside the unit.

To avoid such a problem, you should flush your water heater annually. If your area has hard water, then you might want to install a water softener as well.

How Do I Stop My Water Heater from Making Noise?

What you can do on your own is check, if all the necessary valves are open and make sure that nothing is touching the water heater.

If you are a relatively experienced DIYer, you can attempt flushing the unit yourself (sediment build-up is, perhaps, the most common cause of all sorts of noises in a water heater).

In case you are looking for a quick solution, then you can choose to use a descaling product. Descaling solutions are usually biodegradable, food-safe solutions that can be safely used in a water heater.

The long-term solution would be to install a water softener. You can choose between a wide range of different softeners that can be placed in various locations.

How Do You Fix a Noisy Hot Water Heater?

When choosing a water heater, make sure to pay attention to the unit’s noise level. Some appliances really are a bit noisier than the others.

The best way to keep your unit as quiet as possible is to have it checked by a professional on a regular basis.

You can also insulate the room where the water heater is located or the actual unit, but that may restrict the airflow. Moreover, you might want to be able to keep an eye on the sounds that the water heater is making (just in case).

How Do You Know If Your Water Heater Is Going to Explode?

One of the signs that a water heater might actually explode is a loud popping noise. Sediment build-up that causes the sound might make the unit overheat, crack, or burst.

Read: The Best Temperature For The Water Heater And Why?