am soon to install a quite high powered cooker hood in my new kitchen which will vent into garage then up through the tile roof. Question is i will be using 150mm ducting and already have a purpose made roof tile terminal ,but it only has a 100mm pipe to connect on to, will this greatly affect the performance or will it be ok to fit a reducer to connect to the tile terminal, unfortunately this is the only way i can duct it to the outside. thanks for any input.
