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A thermostatic radiator valve on position 2 (15–17 °C) Installed thermostatic radiator valve with the adjustment wheel removed A thermostatic radiator valve (TRV) is a self-regulating valve fitted to hot water heating system radiator, to control the temperature of a room by changing the flow of hot water to the radiator.
In a closed heating system though, it has no other means of escape and builds up. An air bubble trapped within a radiator means that no hot water circulates in the upper part and so the heating power of the radiator is reduced. If air is trapped within the boiler this may cause pump cavitation or boiling and overheating within the heat exchanger.
Hot water service piping can also be traced, so that a circulating system is not needed to provide hot water at outlets. The combination of trace heating and the correct thermal insulation for the operating ambient temperature maintains a thermal balance where the heat output from the trace heating matches the heat loss from the pipe.
Insulated pipes are commonly used for transport of hot water from district heating plants to district heating networks and for distribution of hot water inside district heating networks. Thermal insulation material usually used is polyurethane foam or similar, with a thermal conductivity λ 50 of about 0.024–0.033 W/(m·K
A radiator is a device that transfers heat to a medium primarily through thermal radiation.In practice, the term radiator is often applied to any number of devices in which a fluid circulates through exposed pipes (often with fins or other means of increasing surface area), notwithstanding that such devices tend to transfer heat mainly by convection and might logically be called convectors.
Insulated hot water supply and return hydronic piping on a gas-fired boiler. Since pipework can operate at temperatures far removed from the ambient temperature, and the rate of heat flow from a pipe is related to the temperature differential between the pipe and the surrounding ambient air, heat flow from pipework can be considerable.
In his 3m cubed test room with a 1 x 0.5 m radiator and walls of average U value 0.44 W/m 2 K, he found that for a radiator temperature of 43 °C the heat flux through the wall behind the radiator reduced from 7.1 to 3.1 W/m 2. Note that the average heat loss in the room was not reduced by such a large percentage as only part of the surface of ...
Not all central heating systems require purchased energy. A few buildings are served by local geothermal heat, using hot water or steam from a local well to provide building heat. Such areas are uncommon. A passive solar system requires no purchased fuel but needs to be carefully designed for the site.