Why is my hot water heater still popping after flushing?

Author: Aurore Lowe  |  Last update: Tuesday, August 12, 2025

The popping sounds you hear after flushing is created by bubbles of hot steam escaping the layer of sediment when your water heater is doing its job.

How to stop a water heater from popping?

Popping noises are usually a sign you need to flush your water heater tank. We recommend calling a professional to flush your tank at least once a year to prevent sediment build-up.

How to get rid of water heater knocking?

To fix it, consider installing water hammer arrestors, securing loose pipes, checking and replacing faucet washers, bleeding air from pipes, inspecting water supply lines, draining the air chamber, or flushing the water heater. If the problem persists, consult a plumber.

Why does my water heater keep popping?

Popping, like rumbling, is most often caused by limescale and sediment build-up within the tank. The sound is created when steam bubbles form under the sediment, then burst as the water heats up.

How do you break the sediment out of a hot water heater?

After you've drained your hot water tank, you can pour a gallon or so of vinegar through it. To ensure the tank gets a thorough soak (try for 6 hours), close the drain valve before introducing the vinegar. Before you restore power to the unit, flush all the vinegar out. Keep it at the right temperature.

Why Is My Water Heater Relief Valve Leaking And How To Fix

How long does it take to flush sediment out of a hot water heater?

On average, flushing a water heater takes about one to two hours, depending on the tank size and the amount of sediment to be removed. This is slightly longer than it takes to drain the tank as you add another step to the process.

How do I know if my water heater has sediment build up?

Here are some telltale signs of possible sediment buildup in your water heater:
  1. Rumbling, popping, or hissing sounds. ...
  2. The water gets warm but never hot. ...
  3. Cloudy or rust-colored hot water. ...
  4. Leaking or faulty pressure relief valve. ...
  5. Cracks in the tank or connections. ...
  6. Decreased hot water flow. ...
  7. Higher gas or electricity bills.

Why is my hot water heater still popping after flush?

You may be wondering, “Why is my water heater making a popping sound?” If your water heater is making a popping, vibrating, or rumbling noise, the likely reason is that there is sediment or scale buildup on the inside of the tank. One of the most common sounds a water heater can make is a popping noise.

How do I stop my heater from popping?

Here are two ways to solve the problem:
  1. Seal and insulate your ducts. Wrapping your ducts in insulation should solve your “cold winter morning” heating duct popping noise. ...
  2. Replace your ducts. Replacing your ducts is usually more cost effective than insulating them.

Is popping in water heater bad?

The popping noise comes from boiling water beneath the sediment. While the noise is not dangerous, excessive sediment can result in several problems for your water heater. Sediment buildup can slow heat transfer and cause overheating, damaging the inner lining and steel tank and ultimately resulting in a leak.

Why is my hot water heater knocking after I flush the tank?

If the knocking sound continues after you flush the tank, your hot water heater likely has a bigger problem than sediment buildup. One of these three things might be the culprit: Faulty gas valve or pilot light. Faulty thermocouple or thermostat.

When should you not flush a water heater?

If you flush a water heater that already has a significant sediment buildup, it can actually cause more problems. Excessive or large sediment pieces can get stuck in the tank drain valve, or end up exiting the water heater and going through the pipes in your home – and neither of those is an easy fix.

Is it bad if my water heater is knocking?

Signs Your Water Heater Needs Repair

If any of the following is happening along with the knocking, it's time to call Schaafsma: Knocking, banging, or popping sounds can mean sediment buildup, water hammer, or heat trap issues. Inconsistent water temperatures or a lack of hot water.

Why does my heater keep popping?

Popping or Banging

There could be a few reasons why heaters make this sound, like dirty burners that need cleaning, or an excessive amount of gas inside the chambers. If you hear a banging or popping sound when the heater shuts off, it could mean your ductwork is contracting as the metal cools down.

How much does it cost to flush a hot water heater?

Expect a pro to charge you between $75 and $200 to come to your home to flush your water heater, depending on where you live. While this cost deters many homeowners from performing this annual maintenance, it can extend the water heater's lifespan by years, making it worth the additional cost.

What makes a water heater pop off?

Answer. The temperature and pressure relief valve is a safety device that is installed at the factory. It is designed to open on a residential water heater, for your protection, when there is excessive water temperature or excessive water pressure.

How do I stop my water heater from popping?

That popping noise probably means there's sediment at the bottom of your water heater tank. The solution? Simple—the tank just needs flushing. You can either flush the tank yourself or call a professional plumber to do it for you.

How do I stop my heater from knocking?

Bleeding your radiators will release any air that may be trapped inside. When air gets into your heating system, it can cause a banging noise because it increases the pressure in the system. Releasing pressure by bleeding the pipes of excess air can stop the banging noise from occurring.

Why does my heater breaker keep popping?

Your HVAC system may keep tripping the circuit breaker because: Your air filters are clogged. Your HVAC system has a refrigerant leak. Your HVAC's capacitor or motor is broken.

How do you know if your water heater is about to burst?

7 Warning Signs of Water Heater Explosion
  • Leaking Pressure Relief Valve. ...
  • A Consistent Popping Noise. ...
  • Rotten Egg Odor. ...
  • Brown Water. ...
  • Gas Leak. ...
  • Improper Bad Installation. ...
  • Neglecting Routine Maintenance.

Why is my hot water heater gurgling after flushing?

Why is Your Water Heater Making The Gurgling Noise? The main cause of the gurgling sound coming from the water heater comes from the Sediment and mineral build-up inside the Water tank. This is common in older water heaters as they tend to get rusty and develop grains inside them.

How do you unclog a water heater drain?

Open the drain valve and insert the wire into the tank. Move it around a bit in order to loosen any debris or sediment that may have formed around the drain. Back-Flush The Drain: the idea here is to use water to push sediment away from the drain valve so that your tank can drain freely.

What is the best way to get sediment out of water heater?

  1. Step One: Turn Off the Power. ...
  2. Step Two: Turn on a Hot Water Faucet in Your Home. ...
  3. Step Three: Shut Off the Cold-Water Valve. ...
  4. Step Four: Secure a Hose to the Water Heater. ...
  5. Step Five: Begin Draining the Water Heater's Tank. ...
  6. Step Six: Flush Out the System.

Can flushing a water heater damage it?

Remember, there are really no downsides to flushing a water heater. Sediment build-up causes damage and it is more expensive to leave it and let it build than to just flush it out regularly.

How long does it take for sediment to settle in a water heater?

If the sediment is not removed, it can cause leaking, cold showers, odd noises, and even shorten the lifespan of your water heater. Depending on the mineral content of your local water supply, sediment may build up over the course of a year, or five years.

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