Hot water line knocking
 

When we turn on the hot water in our upstairs bathroom, either the sink or shower. The pipe will start a steady knock approx. every 5sec. I know its not "water hammer" but not sure what and how to correct it. FYI we are also on a well supply.

Knocking or groaning? Groaning would be the pipe rubbing against the sides of the holes or clamps as it expands in length from heating up.

Almost a tap every 5-10 sec

It happens more being on a well. Air in the water will collect in pockets in the pipes and in the top of the water heater. When the air comes out the sudden burst of air causes the pipes to shake hitting the places where it's a little loose.

Can't believe I have never had this problem (new one on me). Been on well system for 65 of my 66 years, now water logged tanks from before we had bladder tanks, yepp.

I would say it is just the pipes streching from the temp. change, I have that problem with the PVC stack on my furnace.