AHRI Standard 920 for DX Dedicated Outdoor Air Systems

This technical report discusses AHRI Standard 920, which is used for the performance rating of DX Dedicated Outdoor Air System (DX DOAS) units. The document outlines the purpose of the standard, which is to provide a clear method for evaluating the performance of DX equipment that dehumidifies 100% outdoor air to a low dew point. It compares AHRI Standard 920 with AHRI Standard 340/360, highlighting the differences in their approaches to measuring efficiency. While Standard 340/360 focuses on overall cooling efficiency, Standard 920 emphasizes moisture removal capacity and efficiency metrics. The report details the specific performance metrics defined by Standard 920, including Moisture Removal Capacity (MRC), full-load Moisture Removal Efficiency (MRE), and Integrated Seasonal Moisture Removal Efficiency (ISMRE). It also addresses the challenges faced by manufacturers in complying with the standard and the importance of familiarizing engineers with these performance metrics to ensure effective specification of DX DOAS equipment.