"DerbyDad03" wrote in message
...
I know about water hammer - the loud noise associated with a rapidly
closing valve causing the water to slam inside pipes causing them to bang.
I also know most of the solutions - arrestors, expansion tanks, securing
pipes, draining the pipes, etc.

The water hammer I'm experiencing is different.

- Instead of a single loud bang, I get a rapid fire dull
thump-thump-thump almost like the rat-a-tat-tat-tat of a machine gun.
- They happen when just about any faucet, toilet, shower, appliance, etc.
is turned ON or OFF.
- When a device is turned ON, I'll get 4 or 5 rapid thumps lasting a
second or two.
- When a device is turned OFF (even slowly turning off a faucet) I'll get
anywhere from 20 to 50 rapid thumps lasting 3 - 7 seconds.
- It happens with both hot and cold water, single valve devices or dual
faucet fixtures.
- It happens 85% - 90% percent of the time.
- I have drained the system and refilled it. I thought it helped, because
it didn't happen for a few hours, then it started again. It may have just
been the 15% - 20% of the times when it doesn't happen.

Anybody heard of this type of water hammer?

My guess----You might be getting more than one bang because something is
really loose and has plenty of room to move around. The fact that it
happens with either hot or cold suggests that it might be near the location
where the water first comes into the house. This brings to mind this
thought, do you have any pressure regulating valves in the house? Poor
valve response resulting in several shutting and opening cycles could cause
this symptom. As we all know, water hammer can be a very destructive force.
MLD