In article , "toller" wrote:
I bought some 3/8" soft copper tubing, which fits the 3/8" compression
fittings just fine.

I also bought some 3/8" sweat elbows and Ts. They are way too big.

That's because they're made for 3/8 copper *pipe*.

Presumably it is a matter of ID and OD being used for different components?

It's a matter of 3/8 tube and 3/8 pipe not being the same size. 3/8 tube is
3/8 actual ID.

What size sweat fitting go with 3/8" soft copper?

None that I know of. Sweat fittings are for pipe, compression and flare
fittings are for tube.

What are the 3/8" sweat fittings for? I've never seen 3/8" hard copper.

3/8 copper pipe.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?