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Updated Publications, February 2019

Air-Cooled Refrigerant Condensers, Desiccant Dehumidifiers
Standards Updated

From eSociety, February 2019

ANSI/ASHRAE Standard 20-2019, Methods of Laboratory Testing Remote Mechanical-Draft Air-Cooled Refrigerant Condensers, prescribes methods of laboratory testing remote mechanical-draft air-cooled refrigerant condensers.

The standard has been changed to bring the standard into compliance with ASHRAE’s mandatory language requirements. The 2019 revision to ASHRAE Standard 20 incorporates a number of technical revisions, and references have been updated.

The standard was last updated in 1997 and reaffirmed in 2016.

ANSI/ASHRAE Standard 139-2019, Method of Testing for Rating Desiccant Dehumidifiers Utilizing Heat for the Regeneration Process, includes updated references.


ASHRAE Standard 139 provides uniform test methods for rating desiccant

dehumidifiers that use heat for the regeneration process. It addresses the test methods, apparatus and instruments to be used, data to be obtained and calculations needed to confirm valid test results.

ASHRAE Guideline 4-2019, Preparation of Operations and Maintenance Documentation for HVAC&R Systems, covers the format, content, delivery, and updating of operations and maintenance documentation for HVAC&R systems.


The guidelines purpose is to guide those responsible for the design, manufacturing, construction, commissioning and operation of building HVAC&R and on-site generation systems in the preparation and delivery of operations and maintenance documentation.

This guideline can be used for two separate purposes. It can be used in the construction of new buildings that are not commissioned buildings, or it can be used as a guide for existing building documentation as a guideline for O&M documentation.