Hello,

Have the typical Delta single-handle faucet for the kitchen sink.
At least 10 yrs old.

Has the single good size ball type of valve inside the handle.

Whenever we turn it ON, the hot or cold, there is a big "bang" in the pipes.

Am tempted to call it a water-hammer, but I always thought water hammer, in
the true sense of the word, was only when one closed a valve, and the
ensuing pressure wave due to the running water being shut, suddenly, caused
the hammer.

Is this true ?

We have no problem when shutting; only when turning it on.

Anyway, I replaced the small hot and cold top-hat rubber seals and their
springs.
No change. Still happens.

But there is a built in water diverter valve that goes to a hose sprinkler
for cleaning pots and pans, I guess.
We never use the hose.

Think this valve might be actuating and causing the problem ?

Hard to see how, as the end of the hose is of course shut off, so even if
the valve actuates, it is leading to a "closed" section of hose. But,...?

Any thoughts on this would be most appreciated.

Thanks,
Bob