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Is Your Water Heater Making a Banging Noise? How to Fix It

Is an eerie screeching or knocking in the wall scaring off buyers? Is the water heater making a banging noise? Find out about small fixes and repairs you can make to your water heater before selling your house.
Is an eerie screeching or knocking in the wall scaring off buyers? Is the water heater making a banging noise? Find out about small fixes and repairs you can make to your water heater before selling your house.

What is all that banging about?

Water heaters are notorious for making banging noises and other noises. But not all the racket they make is an indication that something is wrong.

So when home buyers get strange looks on their face after hearing a banging from behind a wall? You don’t want to waste money on frivolous plumber visits when you’re looking to sell.

Refer to this handy guide first! We’ll show you potential causes for the noises, what to do about it, and when to call a plumber so your house can sell for more.

Sediment Buildup

Sediment buildup is a common cause of booming, banging noises. How does this cause noise?

Water becomes trapped underneath the layer of sediment. The electric element turns on (or the burner in a gas heater) and begins to heat the trapped water. As the water heats and rises, it explodes through the sediment layer, causing the sound you hear.

While this won’t necessarily damage your unit, it does make it work harder and can reduce its lifespan. Plus, as more sediment builds up, the noise will get louder.

Luckily, cleaning it is easy. Simply follow these steps:

  • Turn off the water heater and the cold water supply
  • Connect a garden hose to the drain valve and place the other end in an appropriate place
  • Open a hot water spigot in the house somewhere (the system needs air to fill the space as the water comes out)
  • Open the drain valve until all the water drains out
  • Flush the tank with the cold water supply a few times until the water runs clear
  • Close the drain and take off the garden hose
  • Leave the indoor hot water spigot open until water begins to run so the air can escape
  • Turn on the cold water supply to fill the tank

As you can see, cleaning out the sediment buildup isn’t too difficult to do yourself. Try to pick a day when your agent isn’t showing your home.

Water Hammering

Another common cause of water heater noises is called water hammering. It sounds eerily similar to someone knocking on the wall.

It has to do with expansion and contraction as your pipes are heating. The right conditions, such as the dishwasher or toilet flushing, will abruptly turn off water entering or leaving the tank. This causes the piper to knock against the wall.

This isn’t something you have to worry about damaging your tank. However, if it is hitting the wall hard enough it could eventually cause damage. Plus, buyers may not appreciate the noise.

The fix is even easier than flushing the tank. Simply install a water hammer arrestor between the device causing the problem and the water heater.

Heat Traps

Many hot water tanks have heat traps designed to prevent heat from escaping the tank (i.e. water from flowing the wrong direction). This is important as it can reduce wasted heat by about 60%. Imagine the effect on your utility bills!

The trouble is, some designs can make light tapping sounds. The sound is normal and not an indication that something is wrong. In most cases, it won’t even be loud enough to be annoying.

If your tenant is complaining, you can swap out the current design for a dielectric nipple.

Partially Closed Valve

What if your water heater doesn’t bang, but screams or screeches? Combine it with water hammering and you might even have buyers convinced that the place is haunted.

Luckily, a screaming water heater is the easiest fix on this list. There is most likely a valve somewhere that is partially closed. This causes water to be forced through a small opening, creating the screeching noise.

Check to ensure that all valves are fully open. This includes any valves throughout the house (such as under the sinks).

Keeping Maintenace Costs Down

If none of these suggestions seem to be the trouble, you may need to call in a plumber to diagnose and fix the problem. This is not the ideal scenario for your home sale. The more money you have to sink into it, the lower your profit.

That’s where a knowledgeable real estate agent is invaluable. They can let you know what repairs will have the best returns when you find a buyer. They know what local buyers are expecting and what they’ll pay more for.

Plus when you sell your home with a Clever Partner Agent, you receive their full services for a flat fee of $3,000 or 1% for homes over $350,000.

Learn more about more ways a Partner Agent can help you sell your home.

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Andrew Schmeerbauch

Andrew Schmeerbauch is the Director of Marketing at Clever Real Estate, the free online service that connects you top agents to save on commission. His focus is educating home buyers and sellers on navigating the complex world of real estate with confidence and ease. Andrew has worked on projects for the United Nations and USC and has a particular passion for investing and finance. Andrew's writing has been featured in Mashvisor, L&T, Ideal REI, and Rentometer.

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