My reading indicates that water hammer is caused when a water source is
turned OFF.

Last night, we turned ON the dishwasher and there was a loud rumbing
noise. I went downstairs and saw the hot water line (downstairs is a
garage with exposed piping) shaking/vibrating pretty severely. This
stopped whenthe dishwasher started washing. No further problems later
when it entered the rinsing cycles.

Given this was our first experience with what I assume to be water
hammer, can anyone confirm the water hammer may occur if a faucet/water
appliance is turned ON? thanks.

-JC-

wrote:
My reading indicates that water hammer is caused when a water source is
turned OFF.

Last night, we turned ON the dishwasher and there was a loud rumbing
noise. I went downstairs and saw the hot water line (downstairs is a
garage with exposed piping) shaking/vibrating pretty severely. This
stopped whenthe dishwasher started washing. No further problems later
when it entered the rinsing cycles.

Given this was our first experience with what I assume to be water
hammer, can anyone confirm the water hammer may occur if a faucet/water
appliance is turned ON? thanks.

-JC-


Dishwashers can indeed cause this kind of hammer.
The inlet valve is usually a "pilot-operated"
type of valve, which means that the solenoid only
controls a small part of the force required to
open/shut the valve. Water pressure does the rest,
acting on a rubber diaphragm.

Sometimes, when worn out, the valve will chatter
open and shut repeatedly, causing the hammer you saw.

Without seeing it in person, that's my best guess
about what's happening.

Jim

Interesting. Can you clarify that the inlet valve you are referring to
is part of the dishwasher? That would be good to know as the
dishwasher was only purchased last June. (Understanding I'd need to
have your suspicion verified by a service person). Thanks.

-JC-