A boiler or steam generator is a device used to create steam by applying heat energy to water.Although the definitions are somewhat flexible, it can be said that older steam generators were commonly termed boilers and worked at low to medium pressure (7–2,000 kPa or 1–290 psi) but, at pressures above this, it is more usual to speak of a steam generator.

A boiler is a closed vessel in which fluid (generally water) is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications,[1][2] including water heating, central heating, boiler-based power generation, cooking, and sanitation.

EFFICIENCY AND CAPACITY OF BOILERS. Two of the most important operating factors entering into the consideration of what constitutes a satisfactory boiler are its efficiency and capacity. The relation of these factors to one another will be considered later under the selection of boilers with reference to the work they are to accomplish.

First and the highest rating is the Heating Capacity or Gross Output. Since this rating allows for the jacket losses of the boiler and distribution piping to be used in the supply of the build heating load, this output should only be used if 1) The boiler is within the heated space, and 2) all or most of the distribution piping is also within ...

Boiler load - the capacity of a steam boiler - is often rated as boiler horse powers, lbs of steam delivered per hour, or BTU. Lbs Steam delivered per Hour. Large boiler capacities are often given in lbs of steam evaporated per hour under specified steam conditions. BTU - British Thermal Units

Condensing boiler manufacturers claim that up to 98% thermal efficiency can be achieved, compared to 70%-80% with conventional designs (based on the higher heating value of fuels). Typical models offer efficiencies around 90%, which brings most brands of condensing gas boiler in to the highest available categories for energy efficiency.

The DOE heating capacity MBH oil fired heating boiler refers to the heating capacity of the boiler. The DOE is one of the best boilers in the market.

The equation relating thermal energy to thermal mass is: = where Q is the thermal energy transferred, C th is the thermal mass of the body, and ΔT is the change in temperature.. For example, if 250 J of heat energy is added to a copper gear with a thermal mass of 38.46 J/°C, its temperature will rise by 6.50 °C.