Alan wrote:
"We can't see inside the tap (or know what type it is), or if it's only
partly open."
By the looks of the orange handle on the valve, I'd say that this is the
type of valve that uses only a 90degree turn of the handle to go from full
shut to full open (ball valve). When the handle is perpendicular to the
longitudinal axis of the pipe it is fully closed. When the handle it
in-line with the pipe axis it is fully open. From the looks of it in the
picture, the handle looks to be about 30 to 35 degs from the perpendicular,
which is slightly less than half open.
There's an excellent cutaway view of a ball valve here:
http://en.wikipedia.org/wiki/Ball_valve
-Mark
