Corrosion on cold inlet

[Sdsvtdriver]

Hello,

I had a new WH installed about 18 months ago (AO Smith). Plumber replaced all connections to the house with new. The cold in and hot out are SS flex lines. I noticed significant corrosion on the cold inlet where the SS line connects to the WH. We suspected it was related to a used up anode rod and replaced with an electrical anode (https://terrylove.com/forums/index.php?threads/anode-rod-and-water-softener.72343/#post-536010 for reference). It turns out the original anode was ok and the electrical anode company suggested the corrosion was caused by a leak. Chalked all that up to a learning experience.

A few months later, the corrosion is returning. (Pictures: https://imgur.com/a/aIceE). I see no water leaking on the top of the WH. The hot side has no corrosion at all, so assuming both nipples are the same metal, there should be no reaction happening. Any suggestions?

 

[Reach4]

Did that fitting up top have a gasket? If not you should have used PTFE tape and/or pipe compound.

 

[Sponsor]

 

[Dj2]

I would replace:
1. the cold side nipple with a brass nipple (3/4"x 3")
2. the cold side flex connector.
Then wait and see what happens.

Do you have any galvanized pipes or connectors/fittings in the plumbing system?

 

[Sdsvtdriver]

Did that fitting up top have a gasket? If not you should have used PTFE tape and/or pipe compound.

View attachment 44711

The SS piece is new and I assume yes, but would have to remove to check. Good call.

 

[Sdsvtdriver]

I would replace:
1. the cold side nipple with a brass nipple (3/4"x 3")
2. the cold side flex connector.
Then wait and see what happens.

Do you have any galvanized pipes or connectors/fittings in the plumbing system?

Thanks. We did #2. AO Smith sent a replacement nipple, but the nipple in my WH has the dip tube attached to it. AO states their drawings for the WH show the dip tube sits in the top of the tank and the nipple screws in, but it’s definitely one piece.

No galvanized stuff. House is PEX.

 

[Dj2]

Your WH shouldn't look like this after only 18 months, when there is no leak.

I would call AO Smith, again and again, and demand a WH replacement under warranty. You will have to talk to a supervise and complain aggressively to get results. Otherwise they will ignore you.

Let us know what AO Smith said.