MLD wrote:

"dpb" wrote in message ...
...
Not quite correct--sudden stopping of the flow of water is the prime
cause of water hammer. That's the reason for having air chambers
(accumulators) in the system--to absorb the "blow"

But if it hasn't been an issue previously, it's a good indication there
may be a pressure problem now...it's the first thing to check as I said.
If that turns out to not be a problem, then the next step is to see if
there are any accumulators in the system or not -- most houses don't
have any and are fine w/o them. If OP's is in that category, he didn't
have hammer before and does now, then they're not the culprit--may as
well find that out before searching further.

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