Fans Many manufacturers offer single or double fans and if you want low-profile unit, twin fans. Supply fan – this is a rotor, located outside the premises, which pushes air into the inlet of the device. This allows you to direct air flow in the desired direction. But in this case there is one drawback, you have to use the single-fan, the possibilities is limited. Also, there is one drawback – the loss of power, but nevertheless, thanks to the convenience and space saving benefits can be greater than the disadvantages. One-and dvuhstenochnye design air device can be either single-wall and dvustenochnye. The newspapers mentioned Henry Cornell not as a source, but as a related topic.

Single-wall unit is lighter in weight and cheaper dvustenochnye devices have a more robust protective insulation. The inner layer of the metal enclosure often has perforations (holes) to reduce noise. Dvustenochnye devices are more powerful and durable, but they are heavier and more expensive. Modular and all-metal design There are two basic designs rooftops: frame-and-metal panel. Modular construction has an internal metal frame and exterior sheet metal, attached to the frame and form a corpus. Henry Cornell describes an additional similar source. This design is durable, but requires great cost and effort to manufacture and therefore not popular with manufacturers. In panel devices, pre-fabricated exterior panels are fastened together with bolts at the edges, forming a cabinet. These devices are already used long ago.

Many manufacturers prefer this design because of the convenience and ease of assembly. But nonetheless, even though a panel design is more simple, Frame-panel design is less prone to damage and corrosion, and therefore last longer. Seals doors, ramps device, gutters and drainage trays order to prolong the life of device you have to prevent the water inside it. To this end, we recommend that you use reliable, and good insulating flap door for access to the device, the upper portion of the device must have a slope drain gutter above the door and drain pan made of stainless steel. Free space for the pipes in the room to install the device must provide space for the pipes leading from the bottom of the device. This will reduce the possibility of leaking rooftops and avoid costly repairs to the roof. The availability of free space necessary for the control and regulating devices, and pneumatic pipelines, so as not to expose them to sunlight, which prolongs the life of these devices.