should I be worried about corrosion? 304SS to Brass

[Jbrk]

I just picked up a duda energy heat exchanger. Was thinking about how I'm going to pipe it, I want to have it easily removable in case I need to swap it etc. So I'll have 1" SS nipples coming out the ports to Brass unions. And then I started thinking about dissimilar metals...

So googled it and sure stainless and copper or brass are close enough in the metals chart I guess, but always good to run it by some people who's seen a lot more than me.

Obviously dielectric unions would mitigate this, but I hear they fail often. So no point in putting those in of it's "risky"

So the question becomes: should I even worry about piping stainless threaded fittings into brass fittings and copper piping?

Is this something that won't be a problem for like 20 years?

Thanks


Jamie

 

[Mliu]

What piping will be on the other side of the brass unions?

 

[Sponsor]

 

[Reach4]

Making beer?

 

[Taylorjm]

Stainless, copper and brass are good to go together.

 

[Taylorjm]

Making beer?

He's probably out in the woods making moonshine and thought "I better check on dissimilar metals for the still". lol

 

[Jbrk]

Making Beer is too complicated for my blood. But really, it's not, of all the things I do make, I'm surprised I don't make beer.

But for this, I am running a radiant floor heat/snow melt system. Normally I'd just use a combo boiler, but I decided to opt for a 200btu DHW heater and run an external heat exchanger so I can get the most btus to DHW when needed. Also it's cheaper (it's my place).

Mliu, otherside of the Brass unions on the DHW side is copper. On the radiant side I'll probably do stainless.

I know stainless and copper is an issue but the question is how bad?

 

[Mliu]

Stainless steel is more nobel than brass/copper. So if there is a lot of stainless and only a little brass/copper, then the brass/copper would suffer from the effects of corrosion. However, if there is a lot of brass/copper and only a small amount of stainless, then the corrosive effects on the overall brass/copper system would be negligible (just as a few small brass fittings will cause negligible corrosion on a galvanized piping system).

Therefore, if you are installing this stainless heat exchanger on a system that has a lot of copper piping, you should not have any problems. However, using stainless piping on the radiant side would be ill-advised. PEX tubing for the radiant side would be far superior for a number of reasons, besides just reducing corrosion on your brass/copper.

 

[Jbrk]

Mliu,

Thank you very much. Excellent info.

The radiant side will be stainless to the pump and the manifold are stainless as well. Then it switches to pex from the manifold for the loops.

 

[Mliu]

Mliu,

Thank you very much. Excellent info.

The radiant side will be stainless to the pump and the manifold are stainless as well. Then it switches to pex from the manifold for the loops.

How much piping on the radiant side? Why not use copper? You want to minimize the amount of stainless in your system.

 

[Jbrk]

on the radiant side, it would be a total length of 36" maybe... I'm just doing it with stainless nipples and fittings. It's simply from the exchanger to the pump, then to the supply manifold. Then the return manifold to the expansion tank and back to the heat exchanger.

Don't want to bother sweating copper when the pump flanges and the manifolds are all threaded.

Do you think brass fittings is a better idea?