I am thinking of installing a 150mm inline fan to an internal bathroom. Could i use a reducer to take advantage of existing 100mm hole on exterior wall.It will need 7m of ducting and will have 2 elbows.The fan has 265m3 extraction rate.Is this powerful enough? thanks gerry.
7m is a long way for one of these inline duct fans, what you are planning will not work very well but it will extract something. If it is to bring something into line with building regs it will not be good enough but if it is to get rid of the odd fart molecule it might.