Knocking water heater-but more...

[CardsnHoosiers]

I've searched the threads for similar problems and followed the typical advice for knocking in a water heater. I flushed the unit and dispersed lots of grit and built up sediment. To flush I left the cold fill line open and then opened the drain drain valve on the bottom flush out the stuff. When I close the drain valve it starts knocking again. If I open ANY hot faucet in the house the knocking stop until I shut the faucet off and then it starts again. We have had some moaning in the hot water faucet of the shower sometimes. When it happens it stops if I turn down the water a bit. Please help.
Is it sediment build up, air in the lines,or poltergeist?

 

[BAPlumber]

I think you have a bad hot valve somewhere. an expansion tank may also help.

try isolating each fixture (angle stops) and see if you can determine where the problem is.

 

[Sponsor]

 

[hj]

knocking

Draining the tank has nothing to do with curing pipe noises, and only a little bit to do with curing noises in the water heater caused by heating the water. What kind of noises will determine what you have to do to cure them, but we would have to be there to reproduce the sounds in order to diagnose and stop them. An expansion tank would do little to help the situation, unless the water heater was at the point where they are originating.

 

[Herk]

It takes a very small amount of hard water sediment in the tank to cause banging noises. The banging is small air bubbles being released as the tank heats. I've heard loud banging from a week-old heater. I don't know of a cure.

 

[CardsnHoosiers]

Thanks for the responses. Not sure what to do other than hire someone to take a look.
Regarding the bad hot water valve, there may be something to that as previously for a while the hot water valve from the shower (located 5 feet from the water heater) used to moan loudly and then when turned down a bit it stopped. Now since the water heater is making noise I have not heard the faucet noise. Maybe a coincedence--I dunno.