Pounding Noises in Your Water Heater – How to Solve Water Hammer and Sediment Buildup

Pounding Noises in Your Water Heater – How to Solve Water Hammer and Sediment Buildup
April 12, 2012 Lorelie

Two of the most common culprits that cause annoying pounding noises in your precious water heater are: water hammer and sediment buildup.

How to Fix a Water Hammer Problem

Water hammer is considered to be the most common home plumbing problem that can be recognized as a banging, thumping and pounding noise.  It could also signify that there is a very serious problem going on that can definitely affect the performance and safety of your water heater.

Typically, this kind of noise problem happens when water moves through the plumbing and the outlet valve is suddenly or abruptly closed, thus resulting in vibration along the pipeline.  Because of the sudden or abrupt change in pressure and the shockwave, the pipes will then usually hit against the house’s framing, which in turn creates a banging, thumping, or pounding noise.

After the water is stopped suddenly, the high-intensity pressure wave that was made will then travel backward and forward, between the point of relief and the point where the stop is, until it dissipates in the plumbing system.

Please keep in mind that even a new water heater can still have water hammer issues.

The Problem - Water Hammer

Actually, the problem with water hammer is not only limited to the annoying banging, thumping or pounding noise, but also it has a destructive nature for plumbing and fittings as well as your entire heating unit.  The high-intensity pressure wave created in plumbing can reach over 60 times.

As mentioned earlier, the excess buildup of pressure in the plumbing system then goes from the pipeline into the tank heater, where permanent deformation will occur.  Usually, the shell of the tank will expand, and by measuring the circumference at different locations along the tank, you will definitely see and comprehend how serious the situation is.

When water hammer occurs, the high pressure that is in the heating system and the pipes banging against the framing members could potentially cause the unstable plumbing system.

For instance, the flue tube that is installed on a gas-powered water heater on one side, and through the wall on the other, may very well collapse.  With deformed vent, flue gases will not be able to find their way out, which of course will cause the flame and gas combustion to spill out from the combustion chamber.

The Solution - Water Hammer

The solution for water hammer problem, which is sometimes requested by a local code, is installing the arrestor.

The arrestor is designed in a way that works much like expansion tanks, with a diaphragm to separate the air chamber from the water in the plumbing system.  The air acts like a cushion, which absorbs the shockwave from the excessive pressure buildup.

You need to find out the source of the shockwave in order for you to install the arrestor close to where it is occurring.

Another solution would be to use an expansion tank or pressure-only relief valve that works like a sacrificial valve to deal with abnormal pressures.

One effective solution for noisy pipes is to design the plumbing pipes properly and replacing the undersized pipes with larger ones.  In the case of an already-existing plumbing system, just wrap the insulation around pipes in order to minimize the rattling noise and then secure the loose ones if any.

Hint:  Should there be any damage on the tank heater because of water hammer issues, the manufacturer is not liable for warranty compensation.

A very common and frequently asked question among consumers is: “Why is my water heater making unusual noises?  How can I tell if it is caused by water hammer, noisy pipes or something else?”  Actually, plumbing is not always the “guilty” one for making different kinds of noises that you can hear whenever you are running a water heater, a dishwasher or a washing machine.  Normally, the rattling sounds may come from a defective seat washer, even if the tap is barely open.  When it comes to a moaning or chattering sound, it may be caused by a buildup of high pressure.  As for ticking noises, it occurs when you open a hot tap and then hot water suddenly runs through the cool hot water pipe.  It may also be caused by the copper pipe that expands due to the high water temperature.

Probably the most common cause of ticking noises and water hammer is if in case your sink or shower and bathtub is utilizing only a single lever faucet or due to washing machine and dishwasher’s automatic solenoid valves.  Sometimes, a simple change of a defective seat washer is the only effective solution.

How to Remove Mineral (Lime) Sediments and Rust Buildup in Your Water Heater

Typically, residues that occur in almost every water heater tank are the result of mineral (particularly lime) buildup and rust.  Sedimentation is considered to be one of the most common problems that can surely affect your water heater’s performance, reduce the output, shorten its tank life, and make your water heater work even harder which means you consume more electricity.  Rust deposits, for instance, are the end result of the aggressive water action, when the tank starts to corrode, often due to lack or failed rust protective elements such as anode rod or metal tank lining.  There are times that the problem with sediment buildup is so severe, thus making the tank hard to clean or it’s not even worth cleaning anymore.  Therefore, purchasing a new electric or gas water heater is necessary.

How can you tell if it is time to flush and clean unwanted deposits from the tank?  The common symptoms with water scale deposits are: low performance, inefficient heating, or unusual noises such as crackling, rumbling, pounding and popping sounds.

When hot water is trapped under lime scale deposits and because of its porous nature, you will hear popping noises, or even sizzling noises (as the hot water boils to steam) when water is trapped next to the heating elements.  Even if the noise disappears because of the change in water scale structure, this does not mean that flushing the tank is not needed anymore.  Thus, be wary that your tank or its heating elements may fail to work.

In every home plumbing system, sediments form as the result of lime buildup.  Lime buildup increases when water is heated; same goes when temperature and water hardness increases and especially when there is higher usage and increased heating surface occurring.  De-liming is then considered a necessity and it has to be included in the regular maintenance and service of your water heater.  As soon as you hear strange noises inside the water heater, you must act quickly.  Deposits are typically oftentimes loose and they are very easy to remove.  If you wait any longer, then the water scale will harden and thus it will make it tougher for you to remove.

Hint: The best way to avoid sediment buildup in your water heater is by subjecting it to regular maintenance, especially by doing some periodic flushing.

One of the most common solutions in order to get rid of lime scale deposits from the tank-type water heater is to dissolve the residue and then flush it using a delimer such as phosphoric acid.

Another common solution is to scrape the sediments manually, but this is time consuming and it will be quite hard to clean the water heater entirely.

Last but not least, by setting the hot water temperature lower, you can reduce the formation of lime scale deposits, and by installing a softener, you can greatly reduce the hardness of water.

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