The installation of your appliance must be undertaken by a competent person in accordance with the installation instructions and the regulations currently in force.  It is mandatory that all gas installers be CORGI registered.

The chimney must comply with the Building Regulations for Class 1 Appliances and must have a minimum 7" diameter and a minimum height of 10ft.  A faulty flue or chimney may result in smoke and fumes coming into the room.

Additional purpose provided ventilation may not be required depending upon model and installation conditions.  

It is recommended that a fireguard complying with BS6539 or BS6778 be fitted for the protection of young children, the elderly or infirm.