Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 28·2.32
Metal liner replacement on appliance replacement
If a chimney has been previously relined with a metal lining system and the appliance is being replaced, the metal liner must also be replaced unless it can be proven to be recently installed and in good condition.
If a chimney has been relined in the past using a metal lining system and the appliance is being replaced, the metal liner should also be replaced, unless it can be proven that it was recently installed and it can be seen to be in good condition.
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