I've seen numerous questions about noisy pipes, but not one like this. I get a groan (not hammer) whenever I turn on the hot water anywhere in the house. House is 50yrs old, rancher on basement with 1/2 bath, laundry and water heater(elec) in bsmnt. Sometimes will go away when cold water is added for a minute or so. Haven't made a changes or repairs in last year or so. Lived in house for 32yrs. This is happening for the first time. Water heater is approx. 10yrs old.
Can feel vibration in cold water feed to water heater and at main line to house from utility.