Steam generated by the boilers was Titanic's sole power source. Steam provided power to the engines, heat throughout the ship, power to the generators (called dynamo's) for the ships' electrical system, the ships' whistles, and power to the winches used for loading cargo and raising anchors. Even the refrigeration plant and the steering motor for turning Titanic's 115 ton rudder relied on steam power.
Titanic had 29 boilers, 24 of which were double-ended and 5 single-ended which contained a total of 159 furnaces. They were located forward of the engine rooms on the tank top level immediately above the ship’s keel. After being lit, it would take as long as 12 hours for the boilers to generate the necessary 215 psi working pressure for the ship. The furnaces could only be stoked with coal one shovelful at a time which required close to 200 fireman, coal stokers, and trimmers. Each boiler was 15 feet 9 inches in diameter, 20 feet long, and each one weighed 91.5 tons and capable of holding 48.5 tons of water.
Maintaining Titanic's daily average speed of 22 knots required 600 tons of coal a day.