LAD Operational Air Flow
Typical perimeter zones utilizing linear slot diffusers require designers to “pick their poison.” Which is more important, heating or cooling modes? Traditional linear diffusers are installed and set up to optimize heating (vertical discharge) or cooling (horizontal discharge) – but never both. As a result, if heating is required in a perimeter zone setup for optimized cooling, the occupants’ comfort suffers. The same is the case for zones initially optimized for heating. The Performance Aire LAD diffuser solves these problems with one diffuser that optimizes air discharge patterns for both heating and cooling modes – automatically!

The LAD diffuser is a unique linear diffuser that automatically changes between the cooling and heating modes. The self-contained diffuser has a thermostatic device that senses supply air temperature to determine if airflow is directed horizontally along the ceiling (cooling mode) or vertically downward (heating mode).

Airflow direction varies by automatic repositioning of the diffuser’s center blade in direct response to the sensed temperature. The diffuser uses the proven technology of bimetallic coils to sense temperature and reposition the blade. The changeover temperature is manually adjustable from the face of the diffuser.

In the cooling mode, the bimetallic device positions the center blade such that air is discharged horizontally along the ceiling from both slots.

In the heating mode, the center blade is positioned to discharge a high-velocity stream of heated air vertically from a single slot.

Application of LAD Diffusers

The application of the LAD diffuser over entry doors is highly recommended.
Vertical warm air flow will greatly enhance the comfort level in the same fashion as an
air wash.


The LAD unit is actually two separate diffusers in one casing, a two slot horizontal throw in cooling, which automatically changes to a single slot vertical throw in heating.

The sweeping motion of the supply air path, most common in other such devices, during the change from the vertical to the horizontal flow position, has been eliminated by the unusual unit design.

A single blade changes the opening size of both slots, and is adjusted to the optimum maximum cool air discharge velocity. The blade pivot point is located to allow the blade to first close the horizontal flow rear opening; second, partially close the horizontal flow forward opening while partially opening the rear slot to a vertical flow position; and finally, stop at the adjusted discharge opening when warm air is supplied.

The LAD unit CANNOT be over-sized. Simple field adjustments will provide the proper discharge openings for both the cool air and the warm air.