thud or knock All aspects of plumbing questions and answers, help, tips and information

[jablake]

i have a emerson heater (electric) for my hot water i have fitted new taps in the shower and the sink i think they are called the lever type when i close the hot water there is a thud if i do it slowly there is no problem also no problem with cold tap any ideas please

[plumbbob]

This is called water hammer and caused by a sudden stopping of water and the energy in the flow results in a sudden bang or thud.

This is most common on the high pressure side so if it is happening in the hot side it is possible there is a short dead end leg of pipe containing trapped air that is suddenly being compressed when the tap shuts off, and the water rushes along this leg and thuds against the end.

[jablake]

thanks for the reply is there anything i can do to stop this
thank

[plumbbob]

Examine all the pipework leading from the hot water cylinder for a branch that doesn't go anywhere and remove it.

After all, it shouldn't be there for health reasons anyway.