Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 31·2.39
Minimum dimensions for access hatches
Access hatches for flues must be at least 300 mm × 300 mm, or larger where necessary to allow sufficient access to view along the flue length.
Access hatches should be at least 300 mm x 300 mm or larger where necessary to allow sufficient access to the void to look along the length of the flue.
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