HVAC Star Practice Exam

Back pressure in a condensate return line is most often caused by a malfunctioning steam trap. The trap is designed to remove condensate from the steam line while keeping steam from passing into the return line. If the trap sticks or fails to open properly, condensate cannot be discharged and starts to accumulate upstream. That buildup creates a higher hydrostatic head and resistance in the return line, pushing back on the system and raising pressure there. Blocking or venting issues in other components can cause related problems, but they don’t create the sustained back pressure in the condensate return the way a faulty steam trap does. An over-sized condensate pump or low steam pressure changes flow or driving force, but they aren’t the common cause of back pressure in the return line.