Final answer:
An outlet on a boiler for sediment discharge is called a drain valve. This valve allows for the removal of sediment to maintain the boiler's efficiency and prevent damage.
Step-by-step explanation:
An outlet on a boiler to permit emptying or discharging of sediment is called a drain valve. The drain valve is specifically designed to allow the removal of sediment and other impurities that can accumulate at the bottom of the boiler. This is a crucial component for maintaining the boiler's efficiency and preventing potential damage. The process involves opening the valve to let out the sediment, usually while the system is off and the water has cooled down to a safe temperature.
It's important not to confuse the drain valve with the pressure relief valve, which is used to release excess pressure from the boiler to prevent over-pressurization that could lead to a hazardous situation. The expansion tank absorbs excess water pressure caused by thermal expansion, and a check valve prevents backflow in plumbing systems.