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Twin Wall - Internal > Selkirk STC 150mm
System Diameter
Please choose your flue system diameter. Most typical installations will be 5” (125mm) or 6” (155mm) and very occasionally 4” (100mm) when the appliance is small and has a low output, commonly seen on boats and huts. Current building regulations, as governed by Document J, require a 6” flue system to be fitted in any new installation, however there are a few circumstances where a 5” system can be used, for example if the appliance has a 5” outlet and is DEFRA exempt. If you are unsure of which flue system diameter to use, ask your installer or contact us at Firebox Stoves and we will be happy to help.
