Steam and Hot Water Distribution, Auxiliaries and Piping
Steam piping
Steam mains need drip legs with traps at low points, at the ends of mains and ahead of every rise or control valve, plus strainers, check valves, expansion loops with anchors and guides, and insulation. Open isolating valves slowly and drain headers before admitting steam. Water hammer almost always traces to a condensate slug, a failed trap, or a valve opened too fast.
Traps and auxiliaries
Know the main trap types and their failure modes. Float-and-thermostatic traps typically fail closed, waterlogging the system; thermostatic traps often fail open, wasting steam; inverted bucket and thermodynamic traps generally fail closed. Symptoms point the diagnosis: a cold drip leg with a hot line suggests a plugged strainer or closed-failing trap, while a trap blowing live steam continuously points to failure open. Pressure reducing valves must have a relief valve on the downstream side, sized for the reduced-pressure condition.
Hot water systems
Circulators, air separators, expansion or compression tanks, flow-control valves, balancing valves and relief valves complete the loop. Air in the system causes noise and poor heat transfer; expansion tank sizing and precharge are frequent calculation questions.
Rule of thumb
Provide a trap station at every low point, at the end of each main, and every 100 to 200 feet of horizontal run, and always ahead of a rise.