Ratteling Copper Pipes

[froddan]

Hi!
I have experienced some loud ratteling in my hot water pipes lately.
I've tried to find to solution, but nothing really seems to match my case.
It seems to only be the hot-water pipes, which is 1/2" copper, and it only rattles when I use either the kitchen sink or the bathroom sink which is next to the kitchen.
The ratteling is quite loud, and it starts after the hot water has been running for some time (maybe a minute or so). It doesn't happen all the time...occasionally I can run it for longer without any problems at all.
If I turn off the hot water when the rattling starts, it normally comes back quickly after I turn on the water.
If I don't turn off the water when the rattling starts, the water flow stops completely after a little while.
No problems with the down stairs water, which is actually "after" the rattling in the pipe maze.
Pipes go like this:
1. Hot water heater
2. Kitchen sink (rattles)
3. Bathroom (rattles)
4. Downstairs bath room - no problems
5. Laundry room - no problems
Thanks for any advice!!!
F

[canoebuilder]

You problem may be simply that the pipe is not hung or supported so it is not hitting something.
Or it may be faulty valves under each sink.
The fluctuation of presure in the water line may bring on the rattle at times.
First, I would try to adjust valves under each sink to a different setting and see if his helps but if it is ill supported pipes you may have to get into the wall or ceiling below to see if hot water pipe is touching anything.
Gerry

[froddan]

That is what I feared, but it doesn't make sense that it would only happen when water is running in two of the rooms. Never in the bathroom that is further down the pipes.
Also, if I don't turn off the faucet when the rattling/hammering begins, the water will stop flowing after a little while. I wouldn't think that would happen if the problem was the hot water pipe hitting a wall....
But I am not the expert, so it is just my own humble thoughts...
Thank You!!!

[canoebuilder]

If the water stops flowing, on its own, the problem is likely in the valves under the sinks and these should be replaced. The seat washer in the valves may have come loose and this could also cause the rattle and the rattle would be amplified in the pipes in the wall.
Did you try ajusting these valves as suggested?
Gerry