Much of our plumbing was redone and new lines were installed. The water pressure has, since, significantly increased plus we've been experiencing water hammer (primarily, but not exclusively, at the washing machine). I have installed small
water hammer arresters which had little to no affect. For the record, we have no expansion tank or, for that matter not even a hot water tank: on demand water heater.

I understand water hammer can be eliminated by emptying, draining, or cleaning the plumbing system's air chambers. However, I don't know if there are any in this house or, if so, where they are.

The house is nearly 100-years old. Was the inclusion of air chambers common practice in plumbing this old or is this something relatively new?

Where are they located? Is there a standard location? multiple locations?

I don't see them in any obvious places in the basement, etc. Might they be hiding in the bathroom/ kitchen walls?

Thank you