ERn2 An ERn 2 uses 63W of power. Therefore, an ERn 2 dissipates 214.956 BTU ERn4 An ERn 4 uses 100W of power. Therefore, and ERn 4 dissipates 341.2 BTU These numbers include the PoE switch, Rack Power...ERn2 An ERn 2 uses 63W of power. Therefore, an ERn 2 dissipates 214.956 BTU ERn4 An ERn 4 uses 100W of power. Therefore, and ERn 4 dissipates 341.2 BTU These numbers include the PoE switch, Rack Power Supply, Paradigm Station Power Module, and the Architectural Control Processor.