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Condensing Boilers

A condensing boiler is a water heating device designed to recover energy normally discharged to the atmosphere through the flue. It can do this through the use of a secondary heat exchanger which most commonly uses residual heat in the flue gas to heat the cooler returning water stream or by having a primary heat exchanger with sufficient surface for condensing to easily take place. The best term for boilers designed to condense on the primary heat exchanger may be "fully condensing."

Thermostatic Radiator Valves (TRVs)

A Thermostatic Radiator Valve, (TRV), is a self regulating valve fitted to hot water heating system radiators. The TRV controls the temperature of a room by regulating the flow of hot water to the radiator.

TRVs consist of two parts, a valve that opens or closes to control the hot water flow, and an actuator that controls the opening of the valve. The actuator adjusts the valve opening based on the temperature in the room via a mechanical linkage or pin connected to the valve. The actuator is usually a plastic unit containing a wax plug, the wax plug expands or contracts as the temperature of the room rises or falls. The plastic unit is preset by a screw mechanism that positions the wax plug a set distance from the connecting pin.

Digital Thermostats

In order to regulate the temperature of your home effectively, it is necessary to have a thermostatic control for your heating system. This essentially tells the heating system when to turn on and when to turn off in an attempt to maintain the target temperature set by the user. Most also have a clock, and time-of-day (and now day-of-week) settings for the temperature, used for comfort and energy conservation.

More expensive models have a built-in PID controller, so that the thermostat knows ahead how the system will react to its commands. For instance, setting it up that temperature in the morning at 7am should be 21 degrees, makes sure that at that time the temperature will be 21 degrees (a conventional thermostat would just start working at that time). The PID controller decides at what time the system should be activated in order to reach the desired temperature at the desired time. Such a control system also attemps to prevent overshooting the desired temperature.

Most digital thermostats in common residential use are programmable thermostats, which will typically provide a 30% energy savings if left with their default programs; adjustments to these defaults may increase or reduce energy savings.

Solar Heating Systems

Solar heating systems use solar energy to provide space or water heating. Such systems can be used to partially or fully heat water for taps and heating. Active solar heating uses pumps which move air or a liquid from the solar collector into the building or storage area.

A typical household solar heating system consists of a solar panel with a heat transfer fluid flowing through it to transport the heat energy collected to somewhere useful, usually a hot water tank or household radiators. The solar panel is located somewhere with good light levels throughout the day, often on the roof of the building. A pump pushes the heat transfer liquid (often just treated water) through the panel. The heat is thus taken from the panel and transferred to a storage container.

Central solar heating systems and solar combisystems store summertime solar energy in a seasonal thermal store for later retrieval in the winter.

Photovoltaic Panels

A photovoltaic cell is a device that converts sunlight directly into electricity by the photovoltaic effect. The energy captured is then stored for later use. Individual photovoltaic cells are assembled to form photovoltaic panels which may be positioned on the roof of your home for optimal solar gain.

Ground Source Heat Pumps

A ground source heat pump is a machine that moves heat from the ground underneath your home (the 'source') to air or water (the 'sink' or 'heat sink') using mechanical work. Most heat pump technology moves heat from a low temperature heat source to a higher temperature heat sink. Heat pumps can be thought of as a heat engine which is operating in reverse. One common type of heat pump works by exploiting the physical properties of an evaporating and condensing fluid known as a refrigerant.


Page Last Updated: 6th September 2009