Do you hear banging or knocking coming from your water system? Often times we get people reporting a banging noise coming from the water system, but there is nothing hitting any of the pipes or parts. This phenomenon is called Water Hammer. How is this caused?
Water hammer is caused when the valves are shut off, and the sudden stoppage of the water causes a sudden spike in pressure which reverberates through the pipes, causing them to rattle and shake, and produce the knocking noise. Areas that commonly have water hammer issues include:
- Flush valves
- Solenoid valves (washing machines, dishwashers and zip boiling units)
- Ceramic disc tap ware
- Full flow ballcocks
- Long runs of pipe
- Worn out valves
What can you do to stop this noise? The solution to this comes by means of a device knows as a Water Hammer Arrestor. What this device does is it provides a comprehensible cushion of air in the system, so when pressure occurs the water is pushed against this air which absorbs this spike. You want this placed as close as possible to the offending valve, pipe or area where the banging is occurring. Depending on the pipework system and how extensive it is, you may need to use multiple arrestors to effectively solve this situation.
Single Chamber Water Hammer Arrestor – A commonly used arrestor, these are most often used on 12mm pipe and are easily installed onto any section of pipe where it is needed. Its sealed air chamber absorbs the energy from pressure spikes in the water pipe system. These arrestors are made of copper and sustain water temperatures up to 80ºC. The benefit of these arrestors are that they can be installed at any angle to the main pipe. If a threaded joint is not available to attach the arrestor, it can be soldered into place on a T-joint and fitted into the existing pipe, taking up little space behind the wall panel.
Mini End Stop Water Hammer Arrestor – This type of water hammer arrestor is designed to be directly attached to the hose connection of a washing machine, dishwasher, or other water-using appliance. It comes with a 90-degree angled fitting and a threaded end and can be used on a range of pipes from 12mm to 25mm. They can be screwed to a threaded fitting or soldered directly into the pipe itself. While they work best installed at 90 degrees, they work at any angle. Like the single chamber arrestors, these only need minimal space behind any interior wall.
Hose Bib Style Water Hammer Arrestor – These are ideally suited to be used directly on the water intake on washing machines, as they can handle higher water volumes pressures than the other types. These have a wide PVC housing with an internal diaphragm to disperse the shock of water flowing through a quick closing valve. They are larger in diameter and therefore not suited for installation inside a wall. They also tend to be the most expensive to purchase and install.
To read more about RMC water hammer arrestors see the following: