A valve to control water flow, operated by the water pressure across it. It is commonly used to maintain a minimum flow rate through a boiler and to limit circulation pressure when alternative water paths are closed (particularly in systems with TRVs).
Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Biogas originates from biogenic material and is a type of biofuel. One type of biogas is produced by anaerobic digestion or fermentation of biodegradable materials such as biomass, manure, sewage, municipal waste, green waste and energy crops. This type of biogas comprises primarily methane and carbon dioxide.
Conventional boiler: Conventional boilers burn fuel in a combustion chamber surrounded by a water jacket, thus heating the water for circulation around a heating system. Much of the heat is lost to the surrounding air or up the flue.; Condensing boiler: Condensing boilers are higher efficiency boilers that waste almost no heat out of the flue. They are designed to extract more heat from fuel than a conventional boiler. These boilers cool the condensation heat from the flue gas so that the water vapour condenses. The heat produced by this process can be used to heat water. Most brands comply with current UK building regulations.; Combination boiler: Modern form of gas boiler which activates on demand usually within a pressurised system to provide instant hot water and central heating (but not at the same time).When hot water is being run there can be no heat to the central heating system. With this form of boiler there is no need for water storage tanks or hot water cylinders.; Wood-burning (biomass) boiler: There is a wide variety of wood-burning boilers on the market, utilising differing wood fuels such as wood, wood pellets, or corn (renewable resources). Burning these fuels adds no net carbon to the environment, thus making no contribution to global warming. Log fuelled boilers need to be fed manually and the logs can take up a lot of storage space.; Automatic-feed biomass boiler: These boilers use wood chips and/or pellets and come with their own storage container where the top-up fuel can be kept and automatically fed into the boiler unlike log fuelled boilers.
No agreed definition, but typically a device intended to improve boiler control using a selection of features such as weather compensation, load compensation, optimum start control, night setback, frost protection, anti-cycling control and hot water override.
This is not a physical device but an arrangement of the system controls so as to ensure that the boiler does not fire when there is no demand for heat. In a system with a combi boiler it can be achieved by fitting a room thermostat. In a system with a regular boiler it can be achieved by correct wiring interconnections between the room thermostat, cylinder thermostat, and motorised valve(s). It may also be achieved by a suitable boiler energy manager.
A device, or feature within a device, to vary the fuel burning rate of a boiler according to measured room temperature. The boiler under control must have modulating capability and a suitable interface for connection.
A device, or feature within a device, to vary the fuel burning rate of a boiler according to measured water temperature. It is often fitted within the boiler casing. The boiler under control must have modulating capability.
Often referred to as BTU, this is the old Imperial measure of heat needed to raise the temperature of one pound of water by one degree Fahrenheit. Sometimes still used to size domestic heating boilers and radiators.
Integrated central control system for electric storage and panel heaters that provides programmed space temperatures at different times of the day for a number of separate heating zones in the dwelling. It minimises the charge period of the storage heaters according to the external temperature.
Capacity factor is one element in measuring the productivity of a wind turbine or any other power production facility. It compares the plant's actual production over a given period of time with the amount of power the plant would have produced if it had run at full capacity for the same amount of time. A conventional utility power plant uses fuel, so it will normally run much of the time unless it is idled by equipment problems or for maintenance. A capacity factor of 40% to 80% is typical for conventional plants. A wind plant is "fueled" by the wind, which blows steadily at times and not at all at other times. Although modern utility-scale wind turbines typically operate 65% to 90% of the time, they often run at less than full capacity. Therefore, a capacity factor of 25% to 40% is common, although they may achieve higher capacity factors during windy weeks or months.
Often referred to as CO2, this greenhouse gas is mostly produced by the combustion of fossil fuels. Its high atmospheric concentrations are a result of human activity which interferes with the natural CO2 cycle. This can cause negative effects, such as rapid climate change.
These utilise parallel rows of glass tubes to absorb energy from the sun. Each tube is transparent and consists of an outer tube and a metal absorber tube attached to a fin. The coating of the fin absorbs energy from the sun.
An energy efficient electric compressor that takes a high volume of low-level heat from one source. This is then transferred to another place as a lower volume of high-grade heat. It operates as a heating and air-conditioning system that uses a refrigeration cycle (where a refrigerant is compressed as a liquid and expanded as vapour to absorb and emit heat.) The heat pump transports heat to a space to be heated during Winter and reabsorbs heat from the same space to be cooled during the Summer. Heat can be absorbed from the air, ground or ground water (see Borehole).Types of heat pump:; Air Source Heat Pump: The most common type of heat pump, it absorbs heat from the outside air and transfers it to the space to be heated. Or, in cooling mode, the heat pump absorbs heat from the space to be cooled and rejects it to the outside air. Back up heating is needed if outside air temperatures are likely to fall to 32 degrees Fahrenheit or below.; Ground Source Heat Pump: A heat pump in which the refrigerant exchanges heat with a fluid circulating through the ground or ground water. The fluid is contained in a variety of vertical and horizontal pipe layouts depending on the temperature of the ground or water and the ground area available. These heat pumps can use the waste heat from an air conditioning system to provide hot water in the Summer. Geothermal heat pumps are more expensive to install but are more energy efficient than air source heat pumps and have lower emissions.; Closed loop: A heating or cooling system where the heat transfer fluid circulates from the heating or cooling components to a heat exchanger thereby transferring heat away.
Illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of the intensity of the incident light, wavelength-weighted by the luminosity function to correlate with human brightness perception.
A unit or measure of energy consumption of 1,000 Watts (one kilowatt) over one hour. Written as KWh. Can be used to measure electricity generation and use as well as the heat energy of fuels such as gas.
Abb. for Low Carbon Building Programme, i.e. a UK Government programme offering grants towards the cost of installing domestic microgeneration technologies and larger scale distributed generation installations for public buildings and businesses, provided energy conservation standards are also met. The programme is split into two phases - phase one, which is further divided into two streams, provides grants for householders under stream 1, and grants for businesses under stream 2. Phase two provides grants for public sector, charitable and third sector organisations. Grants are only offered to installations using products and installers assessed and certificated to robust standards under the new Microgeneration Certification Scheme mark (or its equivalent, for products).
A luminaire is a lighting fixture complete with the light source or lamp, the reflector for directing the light, an aperture (with or without a lens), the outer shell or housing for lamp alignment and protection, an electrical ballast, if required, and connection to a power source
Abb. for Microgeneration Certification Scheme, i.e. a UK Government sponsored certification scheme for products and installers covering all the microgeneration technologies. The MSC is designed to raise standards, protect consumers and to offer information through the certification "mark". It underpins the Low Carbon Buildings Programme (LCBP) which offers UK government grants for installation of microgeneration. Grants are only offered to UK householders and other qualifying applicants who use MCS certified products (or those with a mark accepted as "equivalent") and MCS installers.
A valve to control water flow, operated electrically. A two-port motorised valve controls water flow to a single destination. A three-port motorised valve controls water flow to two destinations (usually for space heating and hot water), and may be either a diverter valve (only one outlet open at a time) or a mid-position valve (either one, or both, outlets open at a time). The valve movement may also open or close switches, which are used to control the boiler and pump.
A control to switch the electrical supply to the main immersion heater from the off-peak electricity supply. It may also include a boost function so that some of the stored water can also be heated using on-peak electricity.
A device, or feature within a device, to adjust the starting time for space heating according to the temperature measured inside or outside the building, aiming to heat the building to the required temperature by a chosen time.
A device, or feature within a device, to adjust the stop time for space heating according to the temperature measured inside (and possibly outside) the building, aiming to prevent the required temperature of the building being maintained beyond a chosen time.
Two switches operated by a clock to control both space heating and hot water. The user chooses one or more on periods, usually in a daily or weekly cycle. A mini-programmer allows space heating and hot water to be on together, or hot water alone, but not heating alone. A standard programmer uses the same time settings for space heating and hot water. A full programmer allows the time settings for space heating and hot water to be fully independent.
A thin layer (less than one micron thick) of material that is deposited onto a metal, ceramic or semiconductor base and is used to make photovoltaic cells. The film can be conductive or non-conductive and can be made of amorphous or polycrystalline material.
An electrical switch operated by a clock to control either space heating or hot water, or both together but not independently. The user chooses one or more on periods, usually in a daily or weekly cycle.