Condensation Overflow Trap 4" 100mmSuitable with 100mm duct, As recommended by both Building Regulations and NHBC guidelines, Domus Condensation Duct Traps effectively remove the risk of condensation sitting in the unheated area of a duct run. The build up of water in a duct run will damage air quality. More dangerously, the water can drip back into an electrical appliance, causing an electrical or fire hazard. The Domus condensation trap is easy to install by simply connecting to the