1/2" sweat to 3/4" Male NPT brass adapter?

CLamb

When I installed my steam boiler a few months ago I used a copper 1/2" sweat to 3/4" Male NPT adapter for connecting to the steel hot water coil, although using a brass one was recommended on this forum in order to prevent galvanic corrosion, because I couldn't find a brass one. Now it looks like I have galvanic corrosion so I must replace it. Does anyone know where I can obtain a brass 1/2" sweat to 3/4" Male NPT lead-free brass adapter? An alternative I have found is a 3/4" nipple and a 1/2" sweat to a 3/4" Female NPT lead-free brass adapter.

Larry Weingarten

Hi, I'm not answering your question directly, but do have a suggestion for preventing further corrosion and making servicing easier. I'd consider coming from the coil in plastic lined steel nipples and then brass unions. From the unions, go to copper. This approach puts distance between different metals and makes access simpler, should things ever need servicing. Here's one brand: https://api.ferguson.com/dar-step-service/Query?ASSET_ID=1394252&USE_TYPE=SPECIFICATION&PRODUCT_ID=1302318

Yours, Larry

Ironman

Why not simply put a 3/4 x1/2” brass bushing on the coil. Then use a 1/2” cu. male adapter?

You’re making it much harder than it is.

You should also have unions as close to the coil as possible and a valving arrangement for cleaning. Get a tankless valve kit, a couple of bushings and brass nipples, and you’ll have everything you need to do it right.

EBEBRATT-Ed

I am not in favor of bushings they tend to leak. I would come out with a short brass nipple with a 3/4 x 1/2 brass coupling.

And alternative is a copper female x brass male union.

What ever you do swest to the fittings before you screw them into the coil. Don't screw the fittings in and sweat to them you will cook the pipe dope and the coil will suck up the torch heat making soldering more difficult.

pecmsg

That looks more like a very minor leak thats causing the corrosion.

Mad Dog_2

I'm always cautious ⚠️ screwing anything in to brazed coils...so soft...Mad Dog 🐕

mattmia2

They are leaking. I would probably do brass fittings to brass valves with built in drain for cleaning and flushing then go to copper from the valve.

archibald tuttle

I would probably not use a tankless coil in the first place :-). just sayin'

mattmia2

https://forum.heatinghelp.com/discussion/comment/1805617#Comment_1805617

At least not for dhw in a residential application. Way too expensive. In commercial applications where there is a constant demand of some sort they can be efficient. They are good for isolating hot water domestic heating loops.

CLamb

@pecmsg @mattmia2 I didn't see any water seeping but now that I have your expert advice I will clean off the corrosion products and take a closer look.

@EBEBRATT-Ed Perhaps I did cook the dope thereby causing a leak when I soldered the fittings. I will try what you suggest.

@Larry Weingarten @Ironman @Mad Dog_2 Thanks for your ideas. I will ponder using them.

mattmia2

You can even see a little water stain under the lower fitting. I'd use dope and thick teflon tape like blue monster or the yellow stuff sold for gas or other thick tape with the replacement fitting.