Brass fitting into water heater

[Bethany533]

Does anyone have an opinion about using brass in the plumbing system with an aluminum water heater? My concern is galvanic corrosion.

[dznf0g]

Well, I'm no expert on the reactivity of various metals...I do remember someone here on the forums is. But I don't THINK that brass vs. aluminum is very corrosive. I do know that my old SOB was 17 years old and I had several brass fittings on a pressure expansion tank system and H2O heater drain valve. Still had the original water heater when I traded for my AS.

[richinny]

read this thread:
http://www.airforums.com/forums/f4/i...num-49955.html

[overlander63]

Originally Posted by Bethany533

Does anyone have an opinion about using brass in the plumbing system with an aluminum water heater? My concern is galvanic corrosion.

That's how they came from the factory. In our 40 year old Airstream, we have an aluminum tank, brass fittings, and copper pipes.

[Kevin245]

Corrosion is a consideration when joining dissimilar metals. The Anodic Index (AI) lists metals in order of nobility with brass being in the 0.40 to 0.45(V) range, and aluminum (other than 2000 series) coming in around 0.9 to 0.95(V).

The rule of thumb is to keep the AI variance to no more tha 0.25(V) in normal conditions. That being said...brass to aluminum isn't a good combination on paper. In reality though, it is commonly used as Terry indicates.

We have brass fittings in our WH and they work fine. Using an application suitable sealant helps minimize the effect.

We also replaced the drain plug with a thumb value that makes draining the WH much easier.

Atwood water heater drain plug - Airstream Forums