Thank you to those who answered accepting the premise of my
question. I will try some cobbling in series, although it is hard
to buy online because I don't know the terms for what I need. I
don't have good access to local plumbing contractor places...
I just found shutoff valves with threads only on the output end,
but will try more.

Above was cold water, but the hot comes from some larger than
3/8 size, where I had to cobble in an extra old flexible hose with
different size ends. I'll guess this is 3/8 to 1/2 and try for a
shorter mating. Also I have a failing shower diverter valve that
a plumber refused to replace (because needing to rip tiles?) and
may try replacing the plain spout with a diverter one to trap the
trickle there, although may have to set the main diverter half way
to pressurize the other diverter seal.

On Sunday, October 7, 2012 9:15:38 AM UTC-10, hr(bob) wrote:
That what it seems like. He/she should be able to shut off the water,
and unsolder or unscrew the present valve and put a new valve in its

I had hoped I didn't have to explain how the tower block in question can't
shut off water except to many units at once, and the rare planned turnoff
can't delay turning it back on earlier than expected due to the extreme
inconvenience to everybody waiting. This troubled bldg has had frequent
long unplanned water cutoffs for 6, 12, or 24 hours and anyone wanting
an open end down period for amateur plumbing is asking for a lynch mob.
I had a lot of trouble getting solder to flow to the heat in a previous house.
Better to just opportunistically slam in a screw in patch in series.