Why Gas Water Heater Making a Humming Noise

Water heaters are not silent appliances. But that’s not necessarily a bad thing as once you get used to the ‘normal’ sounds, it would become much easier for you to notice the strange noises indicating that something is wrong.

Your gas water heater might start humming in case the gas is struggling to get through the line, the gas burner assembly is malfunctioning, the shut-off valve is closed, the unit is placed too close to other objects, or there is a loose component in the water heater.

Are Gas Water Heaters Supposed to Make Noise?

You’ll hear all sorts of noises while a gas water heater is operating, but these sounds shouldn’t be too loud.

Once you get used to the sound of normal operation, it would be easier for you to identify the noises that you should be worried about.

To find out more about the ‘normal’ sounds, you should have an understanding of how the system works.

First of all, there is a cold-water supply pipe that provides the unit with fresh water. There is also a gas supply pipe, a gas valve, and a pilot light or an electronic ignition system that lights the burner.

Finally, you have hot water running through the pipes.

All these elements and processes do produce sounds, but the chances are high that you won’t be paying any attention to those.

Read: Is Furnace And Water Heater The Same?

Why Is There Gas Water Heater Humming Noise?

Here are the main causes of a humming sound in a gas water heater:

  1. A limitation in gas supply – if the gas is struggling to get through the line (the line is bent, damaged, or poorly fitted), then it might start making a humming sound.
  2. The water heater is placed too close to other objects – it is recommended to have 24 inches of clearance in front of the unit and at least 2 inches at the back and sides.
  3. A malfunctioning gas burner assembly – in such a case, you might have to replace the component.
  4. A closed shut-off valve – if the valve is closed or partially closed and the unit is on, then the water won’t be able to make its way further through the system.
  5. Loose components – a humming noise can be caused by the vibrations of some loose components.

Tankless Hot Water Heater Making Humming Noise

If you hear a humming noise in your tankless water heater, then the chances are high that the heating element is loose. When the water flows around such an element, it causes vibrations, and that becomes the source of the noise.

A dirty flow sensor, blocked or inadequate ventilation, and a malfunctioning or improperly installed pressure valve can also make disturbing sounds.

Rheem Gas Water Heater Humming

Some water heaters have flexible connectors that allow you to easily connect the unit with existing pipes.

Inconsistent gas flow might sometimes cause the flex connector to hum. You should also make sure that there are no kinks in the line.

According to Rheem, the problem with a humming water heater can be resolved, in some cases, by installing new burner plates of a slightly different diameter.

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

Why Is My Hot Water Heater Howling?

At times, it’s not your water heater that is responsible for the noises, by the plumbing in your house.

When it comes to a howling sound, the chances are high that you might have trapped air in the plumbing or too much pressure in the lines.

New Hot Water Heater Making Knocking Noise

Usually, a knocking noise would mean that your water heater has sediment build-up that needs to be flushed.

However, if you’re hearing such a sound from a new unit that hasn’t been working for enough time to form a layer of sediment, then it’s most likely ‘water hammering’.

In such a case, the pipes in your house are what’s causing the noise – when the hot water travels through them, the pipes expand and contract, and that’s what is making the knocking noise.

Read: Why Water Heater Is Leaking?

Hot Water Heater Making Noise When Water Is Off

You might not have any hot water running from the taps, but if you have a water heater with a tank, the unit will be in standby mode most of the time. This means that the water is still getting heated, even though it’s not yet being sent through the pipes.

In such a case, sediment build-up could be to blame for a wide range of sounds. Leaks in the actual unit can also cause noises, as well as condensation (the droplets can land on the burner and make a sizzling sound).

Hot Water Heater Makes Noise When Flushing Toilet

Some homes have their toilets supplied with hot water, in order to stop toilet ‘sweat’ – in certain areas, condensation-related issues can get pretty extreme.

If your water heater starts making noises right after you flush the toilet, it might be because the shut-off valve is not open completely or because of water hammering.

When you flush the toilet, a special valve opens to get more water. Once the valve shuts off, the water that has already been rushing to the toilet gets cut off – this pressure is what causes the pipes to make a banging sound.

Read: Gas Water Heater Thermocouple Possible Issues

Water Heater Sounds Like a Jet Engine

What could possibly make your water heater sound like a jet engine?

  • An exhaust blower that is about to go bad, has something stuck in it, or if one of its components had gone loose (in such a case, you’ll be hearing the sound on the side of the house that has the exhaust vent)
  • Air has gotten into the system (this might happen, if you have switched off the water to the whole house or if works were done in the area and the water supply got turned off)
  • The pressure regulator valve between the outdoors and the house is failing

Why Is My Hot Water Heater Making Knocking Sounds?

The knocking sounds are, most likely, caused by sediment build-up.

When hard water runs through the water heater, it leaves behind mineral deposits that then form a layer of sediment. Once you turn the unit on, the hot air bubbles start rising and disturbing the deposits.

The knocking noise is the sediment that is floating inside the tank and clanking against the walls.

How Do I Stop My Water Heater from Making Noise?

  1. Flushing the tank will help in a lot of cases, as the majority of sounds are caused by sediment build-up.
  2. Check and tighten the pipe straps, if you hear a ticking sound.
  3. Make sure that the valves are completely open and that the lines don’t have any deformations or kinks (these issues might cause high-pitched noises)

Calling a professional plumber is always the best idea as the expert would be able to check not only the water heater’s components but also the water’s pressure.

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

How Do You Fix a Humming Water Heater?

Loose components within the unit can make the water heater hum. 

If that’s the case, all you would have to do is turn the unit off and tighten all the parts that might be loose and that are causing the vibrations.

If you don’t feel comfortable working with such units, leave the job to a professional.

What Are the Signs of a Hot Water Heater Going Bad?

Such signs as water leaks, inconsistent water temperature, low hot water supply, low water pressure, and discolored water are the main indications that your unit is about to go bad.

The most easy-to-notice sign is, perhaps, the strange noises that your water heater is going to start making. In general, the louder the noise, the bigger the issue

Can Gas Water Heaters Explode?

Both gas and electric water heater can explode. This might happen, if the pressure inside the unit gets too high, if the water has been improperly installed, or if there has been a gas leak.

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

The main signs of a water heater that is about to explode include a leaking pressure-relief valve, a leaking tank, an always-open T;P valve, and a rotten egg smell.

When it comes to sounds, you should be extra careful, if your water heater starts making popping noises. This sound indicates the presence of sediment which, in its turn, might make the unit overheat or might clog the pressure-relief valve.