When any large appliance in your home starts making unusual noises, it’s wise to be cautious and try to get to the root of the problem.
But is hot water heater knocking dangerous? That’s what we’re going to discuss in this guide.
Is Hot Water Heater Knocking Dangerous?
Thankfully, the knocking noise coming from your water heater does not usually indicate danger. Typically, it’s just a result of a scale build-up made of mineral deposits.
Over time, sediment builds up at the bottom of a water heater from all the hard water that has passed through it. As hot air bubbles in the heater move this sediment around, it may start hitting the inside walls of the heater, which is what causes the noise you’re hearing.
While the scale itself, and the knocking sound it produces, aren’t signs that your water heater is about to explode (which is a lot of people’s first concern), that doesn’t mean you should just ignore it either.
If you allow the problem to continue, your water heater could start to get damaged, and you may notice your heating bill increasing because the heater isn’t able to work as efficiently as usual.
Eventually, the heater could actually overheat as a result, and this could cause numerous safety issues, from leaks to burst valves.
So, in short, while knocking from your water heater doesn’t mean immediate danger, it does mean that your water heater is running inefficiently, and left unchecked, bigger and more dangerous issues could develop.
What To Do About Hot Water Heater Knocking
1. Call A Professional
If you’re at all concerned about the knocking sound coming from your water heater, the best thing to do is get in touch with a professional. This is especially true if you don’t feel confident trying to fix your water heater yourself.
Hiring a plumber to take a look at your water heater will cost you money, but it’s worth it because a professional will be able to fully investigate the issue and conduct a thorough examination of your heater. This means that any additional problems can be caught early.
2. Flush Your Heater
Flushing your water heater is something you should be doing on a yearly basis. You don’t need to call in a professional to do this, since it’s something you should be able to do yourself, although a plumber will also be happy to do this for you if you prefer.
To flush your water heater’s tank, you’ll need to put on hand protection to make sure you don’t burn yourself.
It’s also very important to turn off the heater before you start flushing it. Depending on whether your heater is gas or electric, you might need to turn it off differently.
Use the ‘pilot’ setting for a gas heater, and use the circuit breaker to turn off an electric heater.
Before you get started, make sure the cold water valve is shut, and allow about 30 minutes for the tank to cool down. Even with gloves, there’s a risk of burning yourself if you try to flush the heater before it’s cooled down.
Next, you will need a garden hose, which should connect to the drain valve. This is the valve at the bottom of the tank. Make sure the other end of the hose is above a drain or somewhere else that allows the water to escape without making a mess.
Having opened a hot water faucet to make sure a vacuum isn’t able to form, you can open the drain valve and pull out the tab on the valve that controls the pressure.
The water should start draining out, although you might not be able to see the sediment draining out yet.
Turn on the cold water valve once the water has drained fully. This should get rid of any sediment left in the tank. When you see that the water is clear, you can go ahead and close the drain valve and let the tank fill back up with cold water before turning the heater on again.
Frequently Asked Questions
Can A Water Heater Burst?
Yes, a water heater can burst if pressure builds up too much inside the tank. This is one of the reasons why you should take your hot water heater knocking seriously.
Even though a hot water heater making a knocking sound doesn’t mean you’re in immediate danger of a burst tank, the sediment causing the knocking noise can contribute to building pressure levels inside the tank as well as general wear and tear.
What Are The Signs A Water Heater Is Going Bad?
Knocking and other strange noises coming from your water heater is one sign that your water heater is getting worn out. Other signs include water leaking from the heater, fluctuating temperature and pressure levels, and discolored water.
What Is The Lifespan Of A Hot Water Heater?
The average hot water heater (with a tank) has a lifespan of around 10 years. Usually, if your water heater starts making a knocking sound, it just needs flushing to remove the sediment.
However, if your water heater is more than 10 years old, and you hear this noise, you will be better off having the heater replaced. Old water heaters won’t be able to withstand the wear and tear of sediment hitting the tank for much longer.
Final Thoughts
If your water heater is making a knocking noise, don’t panic. This doesn’t mean that the tank is about to explode – it simply means that sediment has built up at the bottom of the tank, and you’ll need to flush the heater.
With that being said, a knocking water heater should not be ignored. If left unfixed, the sediment build-up can lead to more serious issues later down the line, and some of these can be hazardous, so it’s always best to flush your heater at the earliest opportunity. If in any doubt, call a professional.
Hi everyone! My name is Jason, and I am the founder of HeaterWise.com. Having run my own business as a Heating Engineer for 21 years, I have picked up a few things along the way.
I wanted to create Heater Wise as a place where anyone could come, from far and wide, to find the information that they need.
I hope you will join us here at Heater Wise, to get started on your own journey, to expand your knowledge, and make the best heating choices for you and your family.
