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Doug Miller

In article .com, wrote:
On Oct 23, 12:35 pm, "DonC" wrote:
Gee it sounds like what you are doing is right, and the responses have
been good. One more dumb question: while you are soldering, one end
of the pipe is open to the air, right? (So pressure doesn't build up
inside) -- H- Hide quoted text -

Anyone else think this could be a trapped air problem?

Nope. Trapped *air* is never a problem when soldering pipes; it just doesn't
expand enough to cause any trouble, and the pressure isn't high enough to
force it past melted solder. Trapped *water* is a problem, though: when it
turns to steam, it occupies a thousand times the volume it did as water, and
the pressure can be enough to blow a joint completely apart.

The more I
think about it, just because I had some other nearby faucets open, I
don't think that would release the air, and I really think I may just
need to open the shower faucet (the one I'm installing, and this last
elbow is on the supply side of that faucet). The more I think about
it, it sure seems like it could be air, because the solder often looks
like lava rock, instead of a nice smooth finish.

That's not from air coming out -- that's from steam.

I probably should
have mentioned that earlier, but it doesn't always look that way, just
on some of my attempts, but now I'm thinking even on the attempts
where I got the visible part smooth, there could still be rough parts
that I can't see (i.e.-lines/bubbles where the air

steam

is trying to pass).

is passing

My wife just told me she "heard air" everytime I turned on the water.
Not sure exactly what to make of that.

Doubtless you have air in the lines. But that's not relevant he it's the
water, flashing to steam, that's causing your problem.

I'll open the shower faucet on my first attempt tonight, AND also I'll
be the one standing by the pipes while she turns on the water. Most
of the time the leak was slow enough that I left the water on and
looked for myself, and the leaks were coming from the joint, usually
on one side of the elbow or the other, not something silly like them
coming from the threaded joint (at the shower valve) and running along
the pipe down to that spot.

Let the joints cool off longer, too, before you run water into them.

The trick? Get a slice of white bread -- the doughier the better. Wad it up
so that you can shove a bunch of it far down the pipe; a pencil makes a good
ramrod. Make sure it fills the entire diameter of the pipe. Pack it in both
directions if necessary. While you're soldering, the bread will absorb the
water. When you turn the water on, the water will dissolve the bread and
flush the pipe clean.

Good to know.... although we rarely have plain white bread in the
house, but I'm sure I could borrow a slice from a neighbor (wouldn't
taste very good when I returned it though).

It doesn't have to be white bread. Whole wheat works just fine.

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

It's time to throw all their damned tea in the harbor again.