I created a 4 foot loop on one end and capped a run that goes vertical that perhaps creates a vacumm? Not sure but cold water makes noise but not always.

Look for a sharp bend or kink in the tubing that might be causing the flow to cavatate. Good luck, Tom

Look for a sharp bend or kink in the tubing that might be causing the flow to cavatate. Good luck, Tom

There are no kinks. I used hold down clips. Here's what I did:===>
I had my water main on one side of thge house and the hot water heater was on the other side in the garage (no basements South Florida).
So I ran a HOME RUN PEX line (about 80 feet) from where the water main was to the garage. I first went into a new Big Blue water filter housing with a couple of pressure guages, finally I went backup up the wall with CPVC and tapped into a cold water line just before it feeds into the hot water heater.
I then had to cap the original feed that went up the wall into the ceiling. I capped down low in the kitchen. At the same time I hooked the PEX to the main. I used Oakley Push on Couplers that twisted closed. PEX on one side of the coupler with the CPVC on the other. So I used NO crimps, cinch or compression fits with the PEX... just the two couplers.

The pressure guages on each side of the Big Blue housing is steady at 50 PSI. 39 when washing machine is getting water. I have lots of photos.
Is it possible it is sucking in a small amount of air from old CPVC joints but will not leak any water at all? I'm just a handy person not a plumber, so thanks in adavnce for your response(s).

Bob

Can you track the noise down to a single area? Back to you, Tom

You may have undersized pipes. 1/2" pipe will make friction noise with high demand. Also, make sure all in-line valves are fully open...