Any person who installs an automatic damper to serve a gas appliance shall—
ensure that the damper is so interlocked with the gas supply to the burner that burner operation is prevented in the event of failure of the damper when not in the open position; and
immediately after installation examine the appliance and the damper to verify that they can be used together safely without constituting a danger to any person.
No person shall install a manually operated damper to serve a domestic gas appliance.
No person shall install a domestic gas appliance to a flue which incorporates a manually operated damper unless the damper is permanently fixed in the open position.