Instead through wall, thinking to put the exhaust piping of Air- Conditioner
My flat is on the ground floor with two more floors above me.
I understand that hot exhaust will not fall back in my flat and I do not need to do any packing in the chimney vent.
Piping is flat 1.5cm x 9.5cm
Chimney vent is 17cm x 37cm
Exhaust end of piping I can insert in chimney vent as much as 38cm.
Perhaps in cold season when I may want to use the Air-conditioner for heating I may want whole of Chimney vent blocked.
On examination of the vent I found lot of newspaper stuffed in the vent by previous occupant of the flat. He must have tried to conserve some heat in the flat by stuffing the vent with news papers.