HVAC Ductwork is a free, user-friendly app developed by thebimhouse for Android devices. It is a versatile tool that performs engineering checks and accurately calculates the size of ducts for low-pressure systems. The app is capable of handling rectangular, round, and oval ducts, as well as both metric and IPs units.

The app uses Colebrook's equation to calculate pressure drops and has undergone rigorous testing to ensure its accuracy. It has been compared with McQuay Ductsizer, ASHRAE Duct fitting database, and The Engineering ToolBox, and has consistently produced more accurate results.

During the testing, it was found that McQuay Ductsizer's calculation method is based on the Duct Equivalent Diameter, which causes smaller areas and larger air velocity. ASHRAE Duct fitting database (ADFB) rounds up the result to 0, leading to higher friction loss than the other apps. On the other hand, HVAC Ductwork provides the exact same result as ADFB if the result is rounded up to the same number of decimal places.

Overall, HVAC Ductwork is a reliable and efficient app that can be a valuable tool for engineers and professionals in the HVAC industry.