How are heat emitters rated for heat emission?

Heat emitters are primarily rated for heat emission using the concept of EDR, which stands for Equivalent Direct Radiation. This method provides a standardized way to quantify the heat output of emitters like radiators and convectors based on their surface area and the temperature differential between the emitter and its surrounding air. EDR takes into account the heat transfer characteristics of different types of emitters but essentially focuses on how effectively they can radiate heat into a space.

While wattage, BTU output, and size may relate to heat emission in practical contexts, they don't provide the same level of specificity for comparing various types of heat emitters as EDR does. Wattage, for instance, is a measure of electrical power and does not always correlate directly with the heat output of different heating devices. BTU output is commonly used in various heating applications, but it usually reflects a specific condition or class of equipment, which makes it less universally applicable as a rating for heat emitters when compared to EDR. Size may affect the amount of heat emitted, but it does not provide a direct measurement of performance like EDR does.