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Banging pipes & water hammer noise diagnosis, cure: water hammer noises in plumbing is also called hydrostatic shock. Our page top photo shows a water hammer noise suppression device produced by Oatey and available at building suppliers. This particular water hammer noise suppressor is interesting because it's designed to be added to a hose bib or washing machine hose connection by a homeowner, avoiding having to cut and solder pipes. Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman. Water Hammer Noises in buildings: Diagnosis & CureFor steam heat piping noise, see BANGING HEATING PIPES RADIATORS. Also see NOISE CONTROL for PLUMBING and Sound Control for Plumbing for an extensive list of causes and cures of building plumbing noises. Reproduction of this web page electronically at other websites is prohibited. The articles at this website will answer most questions about plumbing noise associated with water hammer or water surge, including the diagnosis and cure of water hammer noises as well as many other building plumbing system inspection or defect topics. We divide water hammer or banging pipe noises in buildings into two categories:
How to Fix Water Hammer Noises in House Plumbing Systems
Water hammer can damage pipe connections and result in leakage. Water hammer works like this: water passing through a pipe has momentum or velocity. When the valve is shut quickly, the momentum of the water carries it into the valve with considerable force. Since water is essentially incompressible, a large pressure is built up against the valve, and there is low pressure upstream in the pipe. The high-pressure water wants to flow to the low-pressure area. This happens so quickly that a small vacuum is created against the valve as the water moves away from it. This can result in cavitation as the water is pulled back against the valve a second time. This continues back and forth in slowly diminishing shock waves. Pressures up to 600 psi (some sources say 1000 psi) can result from water traveling up to 3,000 miles per hour, for very short periods. Water hammer can result in loud noises in supply plumbing pipes. Water hammer only occurs as valves are closed. If a valve is closed slowly, and the noise does not occur, one can be sure that water hammer is the problem. Water hammer is common with quick-closing electrically operated valves on appliances such as washing machines and dishwashers. Air chambers can be installed to control water hammer, as Carson Dunlop's illustration (above) demonstrates. Causes of Water Hammer / Hydrostatic Shock Include
Cures for Water Hammer or Air Hammer - Hydrostatic Shock Noises in buildings
Also see Sound Control for Plumbing for an extensive list of causes and cures of building plumbing noises. Also see NOISES COMING FROM WATER HEATER for the diagnosis and cure of clanking or thumping noises that may be coming from your water heater or heating boiler. - Adapted with permission from The Home Reference Book Heating Pipe Noises: Banging Pipes on Steam or Hot Water Heating SystemsPlease see our complete articles on heating system noise diagnosis and cure at HEATING SYSTEM NOISES and BANGING HEATING PIPES RADIATORS. Excerpts are below. If it sounds as if someone is down in your BASEMENT or cellar banging on the heating pipes with a hammer, and particularly if your buildijng is heated with steam radiators (see STEAM HEATING SYSTEMS), the noise you hear may be due to water hammer in the steam piping system. In both one-pipe and two-pipe steam heat systems steam rises into the building's heating radiators, forcing air out of the radiator's steam vent (see STEAM VENTS), then making the radiator hot. Inside the hot radiator steam condenses back to water as heat is radiated (by the "radiator") into the room. This steam condensate must drain back into the steam boiler where it is subsequently re-heated to steam to continue the heating cycle. But if the condensate is having trouble returning to the steam boiler your heating pipes may become waterlogged. This happens because when the steam boiler water level drops and is not replenished by returning condensate, the automatic water feeder will just send more water into the boiler. Condensate accumulating in the steam piping (when it should be returning to the boiler) not only water-logs the system, it also means that cooler condensate (water) comes into contact with hotter rising steam in the piping. This contact can cause rapid expansion/contraction in the heating pipes and produces the loud "pipe banging" noise we are discussing. Your heating service technician should be someone familiar with steam heating systems and the proper layout and function of condensate return lines in your home. The tech will look for a problem that is blocking condensate return to the heating boiler, such as a clogged strainer in the system piping, a steam trap clogged with rust, minerals, or sediment, or a similar problem. A separate problem: failure of individual steam radiators to get hot, could also be due to blocked condensate return. If a radiator's steam vent is not working, or if a one-pipe steam system's radiator has settled so that it is no longer properly tipped to send condensate back into the steam pipe (and back to the boiler), that radiator will stop working. But individual radiator troubles do not usually explain banging heating pipes. Watch out: If your heating boiler does not have an automatic water feeder and you've been putting makeup water into the boiler manually, a blocked condensate line and low water in the boiler will eventually lead to total loss of heat when the low water cutoff switch (see LOW WATER CUTOFF CONTROLS) , a key boiler safety device, simply shuts down the boiler. Other causes of heating system noises are discussed at HEATING SYSTEM NOISES. Frequently Asked Questions (FAQs) about Water Hammer problems in building plumbing systemsSome of the FAQs discussed below are adapted from information provided by the Watts Regulator Company in a 1973 publication.[10]Question: does water hammer in my plumbing system cause damage?What effects can water hammer have on my house plumbing system? Other than making noise, does it actually hurt anything? Reply:Water hammer causes a sudden "banging" of water supply piping that creates movement and stresses in the system, not just annoying noise. Water hammer can cause loosening of water supply piping connections, leading to plumbing leaks and related damage Water hammer shocks to the water supply system are more serious at higher operating pressures. On hot water heaters the TP valve is usually set 20 to 30 psi above the anticipated maximum system water pressure. This is high enough that the relief valve won't leak or spill when water hammer occurs in thte system. But at higher water pressures, say 70 psi to 90 psi, the relief valve may be damaged or leak when water hammer occurs. At our article on WATER PRESSURE REDUCER / REGULATOR you 'll see that we recommend against operating a home at pressures above 70 psi because of the increased risk of plumbing system or plumbing fixture leaks. [10] paraphrased Question: will the Temperature & Pressure relief valve protect the hot water tank against water hammer damage?Will the T&P valve protect the tank against breaking from excessive water hammer? - Watts Reply:An "excessive" water hammer is an abnormal but momentary condition that causes a very brief surge in water system pressure. The pressure-relief component of a temperature and pressure relief valve can only discharge a verly limited amount of the surged pressure during the moment of shock of the water hammer event, possibly none. If water hammer is causing frequent opening of the temperature and pressure relief valve there may also be a risk that the frequent passage of hot water through the valve deposits scale that eventually accumulates to a level at which it prevents safe reliable operation of the valve in an emergency. And the fact that temperatures inside the hot water storage tank are elevated above cold water temperatures makes no difference - with the exception of the warning we issue next. Watch out: if the hot water tank is in an abnormal overheated condition, that is water in the tank has become superheated above its atmospheric boiling point water hammer could actually lead to a water heater tank explosion. According to Watts Regulator Company, "Water hammer conditions are believed to be a partial factor in starting off an explosion of overheated tanks besides "pressure heat rupture". [10] paraphrased Ask a Question or Search InspectApediaQuestions & answers or comments about banging pipes and water hammer noise: how to find, fix, or prevent banging water pipes or heating pipes Ask a Question or Enter Search Terms in the InspectApedia search box just below. 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