My hot water pipes are a knockin' -- Why?

[Dazz]

Whenever I run hot water in the house, I hear the pipes knocking as if someone is inside the walls taking a hammer to them. Why is this happening and how do I make it stop? Thanks!

[cateyanne]

My hot water tank does that sometimes, a really loud knocking noise? I'm no expert but someone told me it was excessive sediment in the hot water tank and it needed to be drained more frequently, I've done that and we do hear less knocking but it still does it, on occasion. Maybe someone with some expertise could give some advice. Hope it helps.

[Dazz]

Thanks Cateyanne! Every bit of information helps, so I appreciate the advice. I'l give it a try.

[dkpbxman]

I'm not a plumber but I recently had a problem where, while filling up the tub, the pipes would sometimes start banging very loudly and the water start pulsing.
The problem was traced back to a loose shower stem bibb screw on the hot water side. Tightened it down and there was no more problem. (Course' that meant turning off the water to the house, taking off the handle, pulling off the escutcheon, backing out the entire stem, turning it around and THEN tightening the screw. Put it back in reverse order and then cross your fingers !)