TEMPERATURE CONTROL DAMPER
TCD (TCD-EH with optional electric heating)
The RICKARD TCD is used in conjunction with constant volume diffusers for the purpose of providing a measure of temperature control by the variation of supply air volume. The turn-down ratio is limited to between 50% and 60% of maximum because a greater volume reduction will result in dumping of cold air through the fixed aperture diffusers.
The TCD is therefore ideally suited to applications where the heat load variation is limited, such as internal zones in buildings. Very often these internal zones are open plan and in such cases a single TCD could serve as many as 20 diffusers because the whole zone may be regarded as a zone of uniform heat load. Individual temper-ature control of any one diffuser is therefore not possible unless that diffuser is replaced by a VAV diffuser such as the RICKARD VCD.
The TCD can also incorporate an electrical heater bank to provide heating in situations where the occupied space is overcooled even when the damper is in the minimum air position. In this case it is designated as a TCD-EH (E=Electric & H=Heater) and a longer sheet metal casing is manufactured to incorporate the heater elements. Typically the heater will be energised only when the damper is in the minimum air position.