I have a qn on chimney hood, wonder anyone can enlighten me...my new house was installed with Rinnai RH-90CD chimney hood, however, i notice there was no ventilation for the air to go out. As i went to my frd hse, she install those slim hood, i notice the smoke/air will be suck in from bottom and there will be air coming out from the toop of the slim hood. So, i was wondering how come mine do not have the ventilation for the sucked air to come out after filter, anyone can enlighten me?