Electric Storage Heaters in Building Simulation

sometimes unexpected results which have emerged, and looks to future developments. This paper describes the simulation of electric storage heaters and their controls. A method for modelling manual control, inferred from transformer readings, is described. Use of the dynamic simulation language ESL compiled into a single program with an existing building simulation program, is explained. This provides a powerful and flexible tool for the evaluation and development of storage heaters and controls. Optimisation of storage heater controls has been shown to be a complex process which requires a sophisticated modelling approach. Final choice of the optimal control setting is shown to involve consideration of several parameters. STORAGE HEATERS Figure 1 shows a cross-section of a typical storage heater without a fan. The Feolite bricks which form the core are heated by metal heating elements, similar to the type used in kettles. The special insulation reduces heat loss from the bricks. Heat is emitted radiatively from the case, and by convection through the bricks as shown. The flap at the top, usually operated on a simple thermostat consisting of a bi-metallic strip, opens when the room temperature falls to the set level to increase the convective heat emission. There are various methods of charge control, described below. Some heaters do not allow convective loss by natural convection, but have fans which drive the air through the core; these have better heat retention and greater control. INTRODUCTION Electric storage heaters were introduced into the UK in the 1970s in order to make better use of the load produced by the new nuclear power stations during the night, and to avoid the high daytime peaks associated with direct electric heating. While the spread of mains gas over the last 20 years has meant that many storage systems have been replaced with gas central heating, in the more rural areas storage heating is still widely used. It is also common in urban areas in high-rise flats and local authority housing, and is often an attractive option in newbuild housing which are much better insulated than older stock. AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA AAA convective heat