Smoke leakage (S): Failure of the criterion shall have occurred In case the movement amount in duct A over the check exceeds 10 m³ / (m² h), relevant to twenty °C and 1013 mbar, associated with The interior floor space from the duct Within the furnace. Use a registered installer https://caswell-group55677.anchor-blog.com/16873335/a-review-of-fire-resistant-ductworth-isntallers