Air Handler

Air handlers are sized by cooling or heating capacity in tons, then matched to airflow in cfm against the space's load and the duct system's static pressure. The industry pairs handlers with the plant — refrigerant, chilled water or hot water source. Coil rows, filter depth and fan curves are selected from manufacturer data for the design conditions. A 0–10 ton handler blows chilled water cooling into one room or a small office suite and pairs with a 10 to 20 ton chiller. A 10–25 ton unit conditions a floor, a large tent, or a production area off a mid-size chiller. A 25–50 ton handler serves a large open space — warehouse, hangar, or process area — on a single chilled water loop. Units above 50 tons provide building-scale air handling; several units are usually fed from one large chiller.

• Central air distribution for residential and commercial systems
• Chilled and hot water air distribution in hydronic plants
• Makeup air for kitchens, labs and industrial exhaust
• Temporary conditioned air on construction and restoration projects
• Ventilation air delivery in commercial buildings

• Fan sections are locked out before any coil, filter or belt work — blowers start on remote calls.
• Condensate drains are trapped and tested; overflowing pans above ceilings are a major water damage source.
• Refrigerant coil connections are serviced only by EPA Section 608 certified technicians.
• Access doors on pressurized sections are latched; an open door on a running fan section is a projectile hazard.

AHRI · 430

Performance rating of central station air handling units.

ASHRAE · 62.1

Ventilation for acceptable indoor air quality — governs outside air delivered by handlers.

UL · 1995

Safety standard for heating and cooling equipment.