Hydronics 101 TerminologyA solid foundation for learning a new concept is the terminology associated with that concept.  The Hydronics 101 Terminology and information about BTUs will give you a good base to further your understanding of hydronic heating and the components of various systems.
What is a BTU?

  • A BTU is defined as the amount of heat required to raise the temperature of one pound of liquid water by one degree Fahrenheit. As is the case with the calorie, several different definitions of the BTU exist, which are based on different water temperatures and therefore vary by up to 0.5%.
  • One BTU is approximately:
    • 1 054 – 1 060 J (joules)
    • 2.931 ×10-4 kWh (kilowatt hours)
    • 252 – 253 cal (calories, or “little calories”)
    • 0.25 kcal (kilocalories, “large calories”, or “food calories”)
    • 25 031 – 25 160 ft·pdl (foot-pounds)
    • 778 – 782 ft·lbs (foot-pounds-force)

Associated Units

  • The BTU per hour (BTU/h) is the unit of power most commonly associated with the BTU. The term is sometimes shortened to BTU hour (BTU.h) but both have the same meaning.
  • 1 watt is approximately 3.41 BTU/h
  • 1000 BTU/h is approximately 293 W
  • 1 horsepower is approximately 2,544 BTU/h
  • 1 “ton of cooling”, a common unit in North American refrigeration and air conditioning applications, is 12,000 BTU/h. It is the amount of power needed to melt one short ton of ice in 24 hours, and is approximately 3.51 kW.
  • 1 therm is defined in the United States and European Union as 100,000 BTU—but the U.S. uses the BTU59 °F whilst the EU uses the BTUIT.
  • 1 quad (energy) (short for quadrillion BTU) is defined as 1015 BTU, which is about one exajoule (1.055 × 1018 J). Quads are used in the United States for representing the annual energy consumption of large economies: for example, the U.S. economy used 99.75 quads/year in 2005. One quad/year is about 33.43 gigawatts.

Heating Devices or Systems – Common Terms

  • Boiler, a closed vessel in which water or other fluid is heated
  • Central heating, method of providing warmth from one point to multiple rooms or apartments of a building
  • Convector heater, a heater which operates by air convection currents circulating through the body of the appliance
  • Dielectric heating, the phenomenon in which radiowave or microwave electromagnetic radiation heats a dielectric material
  • District heating, a system for distributing heat generated in a centralized location for residential and commercial heating requirements
  • Fan heater, a heater that works by using a fan to pass air over a heating element
  • Feedwater heater, a power plant component used to pre-heat water delivered to the boiler
  • Fireplace, an architectural element consisting of a space designed to contain a fire for heating or cooking
  • Gas heater, a heater that burns natural gas or liquefied petroleum gas
  • Geothermal heat pump, a heat pump that uses the thermal mass of the Earth to regulate indoor temperatures
  • Geothermal heating a method of heating using geothermal heat
  • Hydronics, the use of water as the heat-transfer medium in heating and cooling systems
  • Induction heating, the process of heating a metal object by electromagnetic induction
  • Radiant heating, a heating system which heats a building through radiant heat rather than convection or forced-air heating
  • Radiator, a heat exchanger designed to transfer thermal energy from one medium to another for the purpose of cooling and heating
  • Solar furnace a structure used to harness the sun’s rays to produce very high temperatures
  • Solar heating, the usage of solar energy to provide process, space or water heating
  • Storage heater, an electrical appliance which stores heat at a time when base load electricity is available at a low price
  • Water heating, the heating of water for residential, commercial or industrial use

Have more questions about hydronics 101 terminology, or are ready to have an expert design a system?  Call May Supply!