Hello group, I am renovating a terraced house to rent out, there is a gas catalytic fire installed in the living room, the room is approx 12x12x8', there is no ventilation in the room other than a 8" trickle vent in the window. I need to get a Landlords CP12 certificate on the building and would like any advice on what would be suitable ventilation for the fire to pass the inspection. I have been informed that a 6" core with a stadium air vent would suffice, but not sure if it has to be a certain type of vent. Would appreciate and advice, apologies for poor second photo, thank you.