Bill wrote:
Two options, low down (30cm) or high up (2.5m) on the wall. The
outside of the wall is onto the street

I would not appreciate a faceful (shinfull depending on height) of
tumble dryer fumes so if your vent MUST be to a public street does it
not have to be a certain height? If the dryer can be vented onto
private ground, animal/insect interest is not a problem with the proper
one way flaps (only time these flaps are open hot/moist air is actually
coming out ). Condensation doesn't seem to be a problem with our set-up
however the prevailing wind is not into the vent and ours (vents into
the back garden) is only 10~20cm above the outlet on the machine.

Thinking out loud :- Will a small s bend in the hose not allow any
condensate to gather and not travel back to the machine. This
condensate will only gather over the last few "puffs" of the tumble
drier and these "puffs" should be of virtually ambient moistness anyway
so will condensate in the evacuation tube be a problem.
--
This post contains no hidden meanings, no implications and certainly no
hidden agendas so it should be taken at face value. The wrong words
may be used this is due to my limitations with the English language .