On Wed, 19 Oct 2005 13:15:30 +0100, "JoeJoe" wrote:


Considering that these fan are only designed to work to their full capacity
with straight ducting of 2-3m according to the manufacturer (mine will be a
pretty messy 4-5m), I just thought that I could get away with using smaller
ducting. Is the only drawback the drop in performance, or is there anything
else I need to consider?

You should use _larger_ ducting in this case.

I should probably add that I am not too concerned with the performance of
the fan, as it is only there to satisfy the BCO demands, and I will happily
live without the fan altogether (personal choice, I know).

The longer the ducting and the smaller the cross section, the more
back pressure you will get and this will reduce the performance of the
fan and it's life expectancy.

M.