I think you are assuming that there is air in the system. Not always the case. Sometimes it can be the shuttle in the tap rattling . My neighbour was forever hooking a piece of hose from the cold water tap onto the hot. Then opening the hot fully & then the cold. Effectively forcing mains pressure cold back up to the hot water tank. Like bleeding your brakes. Eventually he fitted a new tap & it never happened again.

You will find if you close the stop tap upstairs on the tank. You will get little water from your downstairs tap. As it just vacuum's up. Also it could introduce air in through the hot tap. Making things worse. Also is the pipe run clipped tight as a length of copper can start to oscillate if not held firm.

Steve.

It is not uncommon for metal pipes in a plumbing system to bang loudly when a faucet is shut off suddenly, or when a water-using appliance such as a washing machine or dishwasher shuts off the water intake abruptly. It is not normally caused by air in the pipes.

The condition is commonly known as water hammer. The technical term is hydraulic shock, and it occurs when water stops or changes directions suddenly. The banging you hear is caused by the shock wave that causes plumbing pipes to move and strike against one another or against wooden framing members. In addition to being annoying, water hammer can be so forceful that it can break pipes or loosen plumbing joints.

An explanation on Youtube shown here: **LINK**

Paul.

Or you could try fitting a section of flexible pipe in the line, if that is the source of the vibration? Presumably this is a vented hot water supply?

We even put one of the hammer arresters on the outlet pipe of the pump on our traction engine to soften the thumping action of the piston. Made it a lot quieter.

Another option is to use an anti-hammer tap washer. These are spring loaded and close more slowly.  Other types are available from plumbing and hardware stores.

Paul

Edited By Paul Lousick on 13/02/2020 00:22:47

I have had to put in accumulators, similar to the one Bandersnatch referred to, into two different houses.

Martin C

I recently re-plumbed the whole house & fitted a new Combi Baxi boiler. One thing I did learn a long time ago is you cannot have enough stop taps. It makes for easy repairs to the outlets.

Steve.

It's a good idea to go round and fully close/open all stoptaps every couple of years, otherwise when you need to close one you'll find it seized. Don't ask how I know. When you've fully opened it, just close it ever so slightly so it's not against the stop.

On the squealing tap issue, I'm wit Steviegitur above, suspect the tap. Try fitting a new washer.