High Performance Air Systems

Supply Air Temperature

The Therma-Fuser diffuser is a simple stand-alone device that provides VAV control when supplied with air in a suitable range of temperature and pressure.

When supplied with cool air, the Therma-Fuser dampers modulate open on a rise in room temperature. When supplied with warm air, the dampers open on a room temperature drop.

Cool air should be a constant temperature not less than 50°F/10°C for standard models (40°F/4.5°C for model LT-HC) and warm air at a constant temperature of not more than 120°F/49°C. The constant discharge velocity of Therma-Fuser diffusers at varying air flow provides good room circulation which reduces stratification. Keeping heating supply air temperatures as low as possible will further reduce room air stratification to a negligible level.

Changeover from cooling to heating occurs as the supply air rises from 76°F/24.5°C to 80°F/26.5°C and change back from heating to cooling occurs when the supply air drops from 72°F/22°C to 68°F/20°C.

Location and Sizing

Because Therma-Fuser diffusers control room temperature by sensing room air induced up the center of the space, care should be taken not to disturb room air induction and entrainment. For example, location next to walls or dropped lights results in the reflection of primary air back at the Therma-Fuser diffuser. Relocate either the Therma-Fuser diffuser or the light.

Therma-Fuser diffusers are sized for the design or maximum air volume required using the published performance guide. Use a larger inlet size at a lower static pressure when lower sound or NC levels are required and when Therma-Fuser diffusers are at the end of a duct run where less static pressure is available.

Therma-Fuser diffusers may be oversized. They will simply turndown air flow to match the space load. Unlike fixed diffusers used with VAV boxes, Therma-Fuser diffusers won’t dump when turned down.