2022 AO Smith Water Heater with dielectric unions that keep corroding within months

[Danielle Oliver]

I have a AO Smith Water Heater that I purchased in July 2022. I have had to replace the dielectric unions a couple times since. They continue to corrode each time. I sweat the union onto the copper pipe while its not attached to the water heater. Let cool. Then move the water heater into place and connect them. I use pipe tape or dope where the union joins along with making sure the rubber washer is in place. I have tried 2 different tapes. All the sweat joints are fine but wanted to include what I used in case it matters. It always corrodes on the bottom half of the union. There is no visible leaking when joined and I still have not seen a leak. I used a pipe wrench to gently tighten once hand tight. I had a UDI water processor the last 4 years. Could the water softener done this? The last water heater did not have this problem but did fail 2 years after the water processor was installed. Is there a reason they keep failing? Should I try some thing else? I have been told I can use a long brass nipple and just join the brass nipple to the copper pipe. I have to move to a new base with my husband and will be renting my home for 4 years. I don't think it will hold for 4 years till I am back. Any suggestions? At think point I need to replace the nipples. Not sure on the anode or dip tube since I have not taken it apart yet. I need to order those parts since they don't seem to be local to me but wanted to ask here before I move forward with the same unions that don't seem to work.

 

[Twowaxhack]

Those unions and nipples are trash.

 

[GReynolds929]

Ditch the dielectrics and replace the tank nipples with brass. What's going on with the wiring? It looks odd.

 

[MicEd69]

You can use brass or stainless-steel nipples 6" long in place of those couplings.

 

[Danielle Oliver]

Ditch the dielectrics and replace the tank nipples with brass. What's going on with the wiring? It looks odd.

They are wire caps that I had on hand when I moved it last. They are all out since I was moving the water heater again and need to disconnect the power to move it. I will look for brass nipples thank you.

 

[Danielle Oliver]

You can use brass or stainless-steel nipples 6" long in place of those couplings.

Thank you I will look for those!

 

[Danielle Oliver]

Those unions and nipples are trash.

Anything you would suggest to replace them?

 

[Danielle Oliver]

You can use brass or stainless-steel nipples 6" long in place of those couplings.

What kind of union would you use between the nipple and the copper supply line?

 

[MicEd69]

What kind of union would you use between the nipple and the copper supply line?

One of these works quite well.

 

[Danielle Oliver]

One of these works quite well.

View attachment 46490

Thank you!
I will order this.

 

[Twowaxhack]

Anything you would suggest to replace them?

I use fip copper adapters.

I have no reason to install unions because I rarely if ever disconnect the tank unless I’m replacing it. More often than not the new tank has different dimensions so I end up having to alter the piping anyway.

Fip adapters are cheap compared to unions and FIP adapters won’t leak like a union can.

It comes down to preference and I’ve been doing this for years with much success.

 

[Danielle Oliver]

Ok so,

Step 1 - Connect FIP adaptor to a section of supply line.
Step 2 - Connect the section from step 1 to the brass nipple.
Step 3 - Then connect the other end of step 2 to the supply line.

Does that sound right?

 

[Twowaxhack]

I install the nipples into the water heater. Then I’ll take a short section of copper pipe and solder on my fip adapter. Then I’ll go up to the copper 90’s and remove those 90’s.

Then screw my fip adapters with short pieces of pipe soldered in onto the nipples.

Then I’ll mark the copper tube where it intersects with my horizontal copper and cut it. Then I’ll install a new 90 and solder it in.

This keeps you from getting that threaded connection too hot by soldering too close.

Hope that makes sense to you.

But if you want to use unions that’s fine with me, it’s personal preference.

I feel like my way is pretty much leak proof but unions can be nice in some instances. Again it’s just personal preference. If I have a leak then it could involve insurance claims or damage I’d have to pay for. Or at the very least it’ll cost me a trip back across town to repair the leak. That’s very inconvenient. I do a lot of work and I don’t like chasing my tail, so I like to be 100%.

 

[Ludington]

I sometimes wish I could use copper, but I would have to install a neutralizer. Just something else to maintain... don't want that.
(Don't like pinholes) my dad (lives around the corner from me.. no 94 years old) had to replumb his whole house because of pinholes.. no thank you.