The individually designed air handlers are based on a specified combination of features. The key in this case is flexibility.

“You can include so much in custom air handlers,” said Mastromonaco.

Custom choices

To specify a custom unit, the following considerations need to be addressed:

•  Will it be an indoor or outdoor unit?

  This choice depends on “preference and the application,” Mastromonaco stated. Outdoor units are selected to save space and for the aesthetics.

•  What is the desired air volume? This defines the aspect ratio, the size of the unit.

•  What type of application?

•  Any size constraints? Don’t forget to consider jobsite rigging.

•  What functions are desired? These may include:

• Heating (hot water, steam, gas, or electric);

• Cooling (DX or chilled water);

• Availability of a central system (or do we need to do it ourselves);

• Filtration (type of filter);

• Humidification (stand-alone or use steam);

• Dehumidification;

• Return or supply fan;

• Heat recovery; and

• Maintenance considerations.

•  What acoustical requirements — how close to occupied space will the unit be?

•  Any vibration requirements for the structure?

•  What type of fans?

•  Any preferred construction (i.e., galvanized steel, stainless steel, coated, or aluminum)?

•  Finally, what options are desired (receptacles, controls, bearing types, and whether to have piping done at the factory)?

It also has to be decided whether shipping will be one piece, multiple sections, or knocked down for assembly at the jobsite.

Custom air handlers can range from 2,000 cfm, which would be used for processing, up to 300,000 cfm, which would be applied for treating outside air in a large building, said Mastromonaco.

Maintenance access

In order for contractors to perform maintenance, you have to be able to readily access the air handler.

Sizing of access sections is important. Every piece of equipment has to be looked at “to size access doors and panels to make sure you have easy access,” remarked Mastromonaco.

Because, says Carrier, central station air handlers often rely on simple controls that can’t optimize performance, the company offers a package that it says improves control — the AirManager.

“The controller has pre-engineered algorithms for the application,” explained Mark J. Tozzi, controls product manager for Carrier.

It takes into account indoor and outdoor temperatures, humidity levels, and scheduling information to determine and initiate optimum operation.

Application rules are built into the program. It will suggest appropriate components and will flag if an error is made and assist in correcting the error.

Designing and specifying air handlers may have just gotten a bit easier for contractors.