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What Is a Slot Diffuser?

B. Turner
B. Turner

A slot diffuser is a building component used to deliver air to a room. These diffusers serve as a critical component in a heating, ventilation, and air conditioning (HVAC) system. Unlike traditional square or round diffusers, a slot diffuser features a long, narrow design. This special shape makes it easy for builders to fit these diffusers into tight spaces, and helps to conceal the diffuser from view to create a more aesthetically pleasing design. A slot diffuser may also be known as a linear or linear slot diffuser in some areas.

Central heating and cooling systems distribute air through a building using a series of metal ducts. A slot diffuser sits at the duct terminal in each room and allows heated or cooled air to enter the space. Each slot diffuser features a linear plenum, or box that fits above the ceiling. This plenum space helps to improve air flow, and allows air to enter the space at an even, steady pace. The surface of the slot diffuser typically features a set of adjustable fins to further control and direct the flow of air.

Slot diffusers are typically concealed within a suspended ceiling.
Slot diffusers are typically concealed within a suspended ceiling.

Contractors may utilize a number of slot diffuser installation methods. They are typically concealed within a suspended ceiling, but may also be placed in drywall partitions or ceilings. Some designs call for these diffusers to be installed in soffits above a window, or in a built-out area below a window sill. In some applications, the diffuser may even be placed in the floor. In rare cases, linear slot diffusers may also take the place of an exhaust grill to return air from a room back to the heater or air conditioner.

Slot diffuser units offer a number of advantages over traditional square or round diffusers. They are an unobtrusive way to supply air to the room, and are designed to blend in with surrounding finishes. Slot diffusers also provide a high level of control over the design and layout of a space, and allow users to utilize fewer diffusers while supplying the same volume of air flow.

Compared to other types of diffuser models, slot diffusers generally represent the most expensive method of air distribution. An HVAC system equipped with linear slot diffusers will cost more in terms of upfront material costs than one equipped with round or square diffusers for the same volume of air. The linear plenum design also generates more noise and allows for greater pressure drops than more traditional diffuser designs.

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    • Slot diffusers are typically concealed within a suspended ceiling.
      By: Yury Gubin
      Slot diffusers are typically concealed within a suspended ceiling.