Reoccurring copper pipe pinhole leaks

[Tony_Para]

Hello folks, I am hoping some of you may be able to provide you perspective on what is looks like could be a serious problem. I am a complete novice so please bear with me...
Full house renovation with all new pipe work, unvented megaflo cylinder, secondary return, pump, water softer etc.

1. Noticed abnormal and excessive sweating on the cylinder 3bar cold water inlet
2. Secondary hot water pipe connected to the cylinder developed small leak, new elbow replaced, problem solved
3. Continued abnormal and excessive sweating on the cylinder 3bar cold water inlet
4. First pin hole leak (5 pinholes in one area) detected on secondary return, on a straight run, plumber replaced section of piping
5. Second pin hole leak detected on secondary return (6 pinholes in one area), on a straight run, plumber replaced section of piping
6. Baxi engineer replaces 3bar cold water inlet
7. Third pin hole leak detected on secondary return (2 x 4 pinholes in one area), on a straight run, plumber replaced section of piping

This all happened in a period of a few weeks, we still have the water meter moving very slightly when now water is being used. I have read quite a bit and understand it could be due to a multiple of reasons - pitting, bad quality pipe, corrosion, electrolysis, flux residue etc.

Whats your thoughts? Where do I go from here?

1. Claim on home insurance and leak detection specialist
2. Copper pipe failure investigation
3. Go after the builder and his insurance

Obviously very worried about the consequences, if anyone can put our minds at ease or help in any way it would be much appreciated.

Thank you in advance!

 

[Scott_D]

Can you post some pictures?
Is the secondary return all in copper? Is it timed

 

[SJB060685]

The fact that this has happened several times means it’s not a coincidence and there lies a problem.
Putting in copper can be down to several things.
. Velocity of water too high.
. PH levels too small or too high and not within safe working range for copper.
. A hard water area with large traces of calcium and magnesium.
. Residual flux could cause this yes.

The cause needs to be identified before you choose a path to take. For example you wouldn’t want to make a claim on your house insurance if the system wasn’t installed properly.

As mentioned above is the secondary return timed or constant?
What size pipe of copper?
And any idea of the flow rates through the copper pipe?

 

[WC1]

Imo it will probably come to a claim on your insurance.
Check if your policy covers trace and access for leaks.
"Go after the builder and his insurance" - have you discussed with the builder and what was their position?

 

[pycoed]

Are you on mains water? I had the same problem when I moved here 44 years ago & plumbed the house in copper. Then I found that our springwater was highly acidic & caused the same problems of pinholes. I had to replumb in plastic. Mains water not an option here