Furnace (house heating) in the context of Fuel oil

A hearth (/hɑːrθ/) is the place in a home where a fire is or was traditionally kept for home heating and for cooking, usually constituted by a horizontal hearthstone and often enclosed to varying degrees by any combination of reredos (a low, partial wall behind a hearth), fireplace, oven, smoke hood, or chimney. Hearths are usually composed of masonry such as brick or stone. For millennia, the hearth was such an integral part of a home, usually its central and most important feature, that the concept has been generalized to refer to a homeplace or household, as in the terms "hearth and home" and "keep the home fires burning". In the modern era, since the advent of central heating, hearths are usually less central to most people's daily life because the heating of the home is instead done by a furnace or a heating stove, and cooking is instead done with a kitchen stove/range (combination cooktop and oven) alongside other home appliances; thus many homes built in the 20th and 21st centuries do not have hearths. Nonetheless, many homes still have hearths, which still help serve the purposes of warmth, cooking, and comfort.

Before the industrial era, a common design was to place a hearth in the middle of the room as an open hearth, with the smoke rising through the room to a smoke hole in the roof. In later designs which usually had a more solid and continuous roof, the hearth was instead placed to the side of the room and provided with a chimney.

Heating oil is any petroleum product or other oil used for heating; it is a fuel oil. Most commonly, it refers to low viscosity grades of fuel oil used for furnaces or boilers for home heating and in other buildings. Home heating oil is often abbreviated as HHO.

Most heating oil products are chemically very similar to diesel fuel used as motor fuel; motor fuel is typically subject to higher fuel taxes. Many countries add fuel dyes to heating oil, allowing law enforcement to check if a driver is evading fuel taxes. Since 2002, Solvent Yellow 124 has been added as a "Euromarker" in the European Union; untaxed diesel is known as "red diesel" in the United Kingdom.

In thermodynamics, the thermal efficiency (${\displaystyle \eta _{\rm {th}}}$) is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, steam turbine, steam engine, boiler, furnace, refrigerator, ACs etc.

For a heat engine, thermal efficiency is the ratio of the net work output to the heat input; in the case of a heat pump, thermal efficiency (known as the coefficient of performance or COP) is the ratio of net heat output (for heating), or the net heat removed (for cooling) to the energy input (external work). The efficiency of a heat engine is fractional as the output is always less than the input while the COP of a heat pump is more than 1. These values are further restricted by the Carnot theorem.

A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust gases or smoke produced by a boiler, stove, furnace, incinerator, or fireplace from human living areas. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the stack, or chimney effect. The space inside a chimney is called the flue. Chimneys are adjacent to large industrial refineries, fossil fuel combustion facilities or part of buildings, steam locomotives and ships.

In the United States, the term smokestack industry refers to the environmental impacts of burning fossil fuels by industrial society, including the electric industry during its earliest history. The term smokestack (colloquially, stack) is also used when referring to locomotive chimneys or ship chimneys, and the term funnel can also be used.

A hammam (Arabic: حمّام, romanized: ḥammām), also often called a Turkish bath by Westerners, is a type of steam bath or a place of public bathing associated with the Islamic world. It is a prominent feature in the culture of the Muslim world and was inherited from the model of the Roman thermae. Muslim bathhouses or hammams were historically found across the Middle East, North Africa, al-Andalus (Islamic Iberia, i.e. Spain and Portugal), Central Asia, the Indian subcontinent, and in Southeastern Europe (notably Balkans and Hungary) under Ottoman rule.

In Islamic cultures the significance of the hammam was both religious and civic: it provided for the needs of ritual ablutions but also provided for general hygiene in an era before private plumbing and served other social functions such as offering a gendered meeting place for men and for women. Archeological remains attest to the existence of bathhouses in the Islamic world as early as the Umayyad period (7th–8th centuries) and their importance has persisted up to modern times. Their architecture evolved from the layout of Roman and Greek bathhouses and featured a regular sequence of rooms: an undressing room, a cold room, a warm room, and a hot room. Heat was produced by furnaces which provided hot water and steam, while smoke and hot air was channeled through conduits under the floor.

A basement is any floor of a building that is not above the grade plane. Especially in residential buildings, it often is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, car park, and air-conditioning system are located; so also are amenities such as the electrical system and cable television distribution point. In cities with high property prices, such as London, basements are often fitted out to a high standard and used as living space.

In British English, the word basement is usually used for underground floors of, for example, department stores. The word is usually used with buildings when the space below the ground floor is habitable and with (usually) its own access. The word cellar applies to the whole underground level or to any large underground room. A subcellar or subbasement is a level that lies below the basement or cellar.

Flue gas is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases, as from a fireplace, oven, furnace, boiler or steam generator. It often refers to the exhaust gas of combustion at power plants. Technology is available to remove pollutants from flue gas at power plants.

Combustion of fossil fuels is a common source of flue gas. They are usually combusted with ambient air, with the largest part of the flue gas from most fossil-fuel combustion being nitrogen, carbon dioxide, and water vapor.

The annual fuel utilization efficiency (AFUE; pronounced 'A'-'Few' or 'A'-'F'-'U'-'E') is a thermal efficiency measure of space-heating furnaces and boilers. The AFUE differs from the true 'thermal efficiency' in that it is not a steady-state, peak measure of conversion efficiency, but instead attempts to represent the actual, season-long, average efficiency of that piece of equipment, including the operating transients. It is a dimensionless ratio of useful energy output to energy input, expressed as a percentage. For example, a 90% AFUE for a gas furnace means it outputs 90 BTUs of useful heating for every 100 BTUs of natural gas input (where the rest may be wasted heat in the exhaust). A higher AFUE means higher efficiency.

The method for determining the AFUE for residential furnaces and boilers is the subject of ASHRAE Standard 103. A furnace with a thermal efficiency (η_th) of 78% may yield an AFUE of only 64% or so, for example, under the standard's test conditions. When estimating annual or seasonal energy used by combustion devices, the AFUE is the better efficiency measure to use in the calculations. But for an instantaneous fuel consumption rate, the thermal efficiency may be better.