Ducted Package Roof Top Systems, Economisers for Fresh Air and Free Cooling

We have previously described the function of a package type system, apart from being able to supply heated or cooled air, the systems we install have an option of an economiser, and this acts as a mixing box and joins the fresh air to the recirculated air via motorised dampers. The fresh air dampers can be adjusted to always provide a minimum amount of fresh air based on the occupancy of the space being conditioned, this eliminates the need for a separate ventilation system, the fresh air dampers are modulated using either dry bulb temperature or enthalpy control.