Example - for a 3-bedroom, 2,000-sq.ft. home, with an exhaust-only ventilation strategy, and a target ventilation rate of 50 CFM you would need to install a 50 CFM fan with an adjustable-speed DC motor for continuous operation.
Quick Answer. Trenches were built during World War I to protect stalemated troops on both sides from artillery and rifle fire. Although the war began with rapid movement of the German army, when the Allied forces stopped the Germans, both sides dug trenches to help avoid losing territory they had gained.
The ocean trenches are narrow topographic depressions in the sea. These trenches form the deepest points in the ocean and are the lowest points on earth. These trenches are formed at a particular place of plate boundary which is known as subduction zone.It happens to form when a plate in ocean hits another ocean plate or it strikes with continental plate.ow when one plate hits another plate or continental plate in the ocean then the denser plate between the two of them sinks in the mantle. The place where this plate sinks will create a deep trench on that spot of ocean.