Thursday, April 21, 2016

FlexRight - Improving Inlet Conditions to Increase Thermal Comfort

The purpose of a heating, ventilation and air-conditioning system is to provide thermal comfort to the occupied space. The ability of an HVAC system to perform this function depends on system design, equipment, air-outlet type, and inlet conditions. Proper inlet conditions at the air outlet is perhaps the simplest and most overlooked factor. It is something that has a direct effect on the level of thermal comfort in the occupied space.

When air distribution is designed for an occupied space, the outlet velocity of the supply air from a diffuser is assumed to be uniform. This is the case when the supply-duct connection at the diffuser inlet has a sufficient amount of straight duct to ensure the supply air enters the diffuser in a uniform pattern. In reality, inlet-duct connections in the field rarely have an adequate amount of straight duct to ensure an even flow of supply air into the diffuser. For the most part, this is due to space limitations in the ceiling plenum, increased costs, and time constraints during installation. In addition, the use of flex duct as a replacement for hard duct has compounded the problem. As a result, a less than optimum duct connection at the diffuser is being used. It provides a non-uniform air pattern in the occupied space with a decrease in thermal comfort (Figure 1).

To address this problem, a simple and easy solution called the “FlexRight” is available from Titus. FlexRight is a plastic 90-degree elbow that connects the flex duct to the diffuser inlet with a gentle 90-degree transition. This eliminates the problem of kinking or improper positioning of the flex duct that is often found in the field when connected to supply diffusers (Figure 2).

FlexRight is made of 100% recycled material, UL listed, and saves energy by reducing pressure loss in the system. The universal design accommodates all flexible duct sizes and diffuser inlets from 4” to 16”. It provides a less expensive alternative to hard-duct transitions and is easy to transport as well as install. With its simple and universal design, FlexRight is a great choice for both new construction and retrofit applications.

Return grilles, and sometimes supply grilles, are specified for lay-in applications. If the grilles are to be connected to ductwork, a grille size is specified as well as the lay-in module size.

Please direct questions toward Titus Communications ( and/or Titus' GRD Product Manager Mark Costello (