Whirlpool DryAire LMA1053L Specifications download pdf (Page 37)

14.0. Outside Air Pre-Heating Requirements

DryAire Systems require that outside air be pre-heated if mixed air temperatures inside the

dehumidifier might fall below 45°F. To determine if an application requires pre-heating of

outside air, follow simple guide.

14.1. Data required:

A. Design return air temperature. (Industry standard is 82F.)

B. Outside air at winter design temperature. Use values as specified by

design engineer, architect, or ASHRAE tables.

C. Total system CFM (dehumidifier unit) and required outside air CFM.

14.2. Determine worst case scenario for Mixed Air Temperature using the following equation:

MAT=(winter temp °F) x (OA CFM) + (return air temp °F) x (system CFM - OA CFM)

(system CFM) (system CFM)

14.3. If Mixed Air Temperature is less than 45°F, then the pre-heating of outside air is required.

Note: Outside air duct must be insulated to prevent condensation which may form

on the exterior of the duct during cold winter months.

14.4. Example: DRY-30-230-1 dehumidifier (2200 system CFM)

Pool Room Project, 400 CFM of outside Air.

Location, St. Paul, MN. winter temperature condition -16°F.

MAT = (-16°F) x 400 cfm + 82°F x (2200 unit cfm - 400 cfm) = 64.1°F.

2200 cfm 2200 cfm

Conclusion: No need to pre-heat outside air cfm.

15.0. Compressor Failure

Some compressors fail because they are mechanically flawed, most failures are due to system

related problems. Compressor failure can be caused by air or moisture in the refrigerant system,

solid contaminant’s, excessive heat liquid flood back or electrical service malfunctions. To avoid

repeated callbacks, you must determine the cause of the failure and then correct it.

If the compressor failed because its motor has burned out, the refrigerant, oil, and piping may have

become severely contaminated. If a burnout has occurred, use the following procedure to replace

the compressor and clean the refrigerant system.

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Whirlpool DryAire LMA1053L Specifications Page 37