If you’ve never heard of water hammer, you’ve probably never heard water hammer. Water hammer is your plumbing’s reaction to valves in your system opening and closing quickly. The sound – which can be loud and sometimes scary – is a result of fast-moving water hitting a suddenly closed valve. It’s essentially a type of shock inside your pipes.
Water hammer can be more than an annoyance. It can also cause damage to your pipes and appliances. When a valve is open in your plumbing system, the water – which is still under pressure – is flowing. Some fixtures need to control water flow quickly and precisely. That would include your washing machine, dishwasher, and toilets; you definitely don’t want these devices overflowing! Standard faucets can also trigger water hammer, but because you manually control their shut-off, they’re less likely to cause it.
Water travels in one direction in your plumbing. When a valve closes quickly, the water stops exiting the system instantly – but it’s still being pushed by the municipal supply. When the flowing water hits a closed valve, it does so with a lot of force. The shock of impact transfers to the rest of your system (and all of the attached fixtures), as the system tries to absorb this blow. That’s when you hear the pounding and banging associated with water hammer. This noise may not be a one-time event. It may take the system a few tries to distribute the shock force effectively.
The effects of water hammer
As you might imagine, over time, this kind of abuse takes its toll on your plumbing. Water hammer can damage faucets and fixtures to the point of leaking. It can also damage appliances over time. Finally, if the pressure from the municipal supply is very high, water hammer can cause pipe damage! In short, water hammer is a situation you will have to address, one way or another.
In some plumbing systems, water hammer is all but guaranteed. The longer your supply line from the municipal system, the more likely you are to experience water hammer. Since you’re unlikely to be able to shorten your supply line, you can modify your plumbing to accommodate the shock.
Another component of water hammer is how the offending valve is being closed. Usually, appliances like washing machines and dishwashers have automatic valves. These valves open and close suddenly and precisely because the appliance mechanically controls them. This is another situation that you probably can’t change, but it can cause water hammer.
Also, municipal systems operate under higher pressures because they have to deliver a lot of water to a lot of customers. It’s entirely likely that the pressure from your municipal supply is too high for your plumbing. This also causes water hammer.
Correcting water hammer
Water pressure is actually one element of water hammer you can control. You can place a regulator on your system just after the meter to reduce the incoming water pressure. If you have a serious problem with water hammer, or chronically leaking fixtures, you might want to have your incoming pressure measured and regulated.
The other, more common way to address water hammer is to install air chambers near the offending valves. An air chamber is a closed, vertical add-on to your plumbing system that normally stays empty. When an appliance valve shuts off, the extra pressure compresses the air in the chamber, giving the shock wave somewhere to go.
If you’re experiencing water hammer and you already have air cushions in your system, it’s possible that they’ve just filled with water. To correct this, you can turn off the shut-off valve(s) to that part of your plumbing system, open the closest tap and let the water drain out. This will empty the air cushion(s). Open the shut-off valves again, and the system should operate quietly. You may have to repeat this periodically if your system is prone to water hammer.
If you don’t have air cushions, a plumber can install them. This will reduce the wear and tear on your plumbing and your appliances. It’s a good solution to counteract the causes of water hammer that you can’t control. It will also save you money by eliminating the need for repairs for your fixtures, appliances and plumbing.
If you’re experiencing water hammer and you would like to correct it, please contact us at Boston Standard Company at (617) 288-2911. We’ll be happy to help you eliminate water hammer in your home.
Photo Credit: Bill Smith, via Flickr
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