Knocking sound from hot water pipe?

Question

In my new home, 1st time in the morning when I open hotwater tap downstrairs, we get a knocking sound from attick which last for about a minute. (it is a nuisance as it wakes up people who are still sleeping). The maintenance checked lines and added some support clamps but still it persists.
Can you help me.

Answer 1

First try this:

To re-establish the air cushion, turn off the water at the water meter, then turn off the water supply to each toilet and the washing machine and dishwasher. Go to the sink closest to the water main and turn on the cold water tap. Then go to the sink farthest away from the water main and turn on that cold water tap (If you live in a 2-story house, that will be on the second floor).

Let all the water drain out of the system, then turn off the top and bottom faucets.

Turn on the water at the meter, then open the valves to the toilets and washing machine.

Turn on each hot and cold-water faucet and flush every toilet.

Be prepared for a lot of banging and spitting as you exercise the faucets and the toilets. It may sound like they are exploding. After the tumult, you will have re-established the air cushion in your water system, and it should operate quietly

Single lever faucets, some water heaters or the automatic solenoid valves in dishwashers and washing machines often cause a water hammer effect. The faster the water valve closes, the greater the shock to the water pipe.

The best remedy is to install water hammer arrestors as close to the source of the closure as possible. The arrestors prevent damage by absorbing the shock wave in an air cushionSingle lever faucets, some water heaters or the automatic solenoid valves in dishwashers and washing machines often cause a water hammer effect. The faster the water valve closes, the greater the shock to the water pipe. .

Answer 2

sounds to me like the noise you hear is the hot water pipe heating up and expanding after cooling off all night maybe some pipe insulation might help.

Answer 3

Open the faucet slowly till into your desired water speed.

Answer 4

Air in the line.