Brass Compression fitting direct from Copper tubing to Water Heater?

[bbazzett]

Just replaced my water heater, and my father in law came by to view my handiwork. He said he "thinks" that having a just a brass compression fitting between the copper pipe and steel nipples on the water heater will cause a "chemical reaction", and will "eat the pipe" over time. He said having a dielectric union inline instead would prevent this from happening.

I know next to nothing about these things, I was just happy it didn't leak and spray all over the place. My father-in-law is fairly knowledgeable, but he himself wasn't certain on this, just trying to give me a warning of possible things to come. I'd like to learn more, and would appreciate anyone weighing in with their knowledge on the subject. Thank you.

 

[havasu]

For a few bucks, the big box stores sells a dielectric union which I always install on top of the W/H.

 

[SHR]

Your father-in-law states the conventional wisdom that has been spread as fact for 20 years. It is not his fault. I think your brass coupling will do a better job than any di-electric union. I quit using them after the 15th time I replaced a water heater due to the di-electric unions disintegrating and causing the water heater to rust out. They are good for my repeat business but I prefer my customers have quality installations. I now only use brass unions at the water heater connection. No more corrosion problems.

Your brass compression fitting will be fine.

 

[Matt30]

What he is referring to is galvanic corrosion, not some old myth it's very real. It's been giving plumbers hell for many years!

 

[SHR]

What he is referring to is galvanic corrosion, not some old myth it's very real. It's been giving plumbers hell for many years!

I know he is. My extensive experience has shown me di-electric unions accelerate rather than prevent galvanic corrosion. Brass between copper and steel seems to stop the corrosion.

 

[Matt30]

I know you know. I was trying to inform the original poster

 

[Matt30]

For what it's worth, I side with SHR when it comes to di-electric unions. I have replaced more then I have installed

 

[bbazzett]

So, if I'm getting this right, the consensus seems to be that the compression fittings will be ok over the life of the water heater?

I appreciate the feedback. Thank you.

 

[SHR]

As long as you installed them so they do not leak; Yes.