LearnMetrics - Home Of Specs-Based HVAC Recommendations, With a little help, every HVAC system can be boiled down to a number of metrics such as BTU, EER, maximum dry airflow, and so on. This is true for all HVAC systems: air conditioners, heaters, dehumidifiers, boilers, you name it. Everything that is built on the principles of thermodynamics, fluid mechanics, heat transfer, and other ... Read more.