At what pressure does a steam-heating boiler operate when not exceeding this threshold?

The correct choice reflects the typical maximum allowable pressure for residential steam-heating boilers, which is 15 psi. Operating at or below this pressure helps ensure safety and efficiency in the system. Steam systems rely on pressure to circulate hot water or steam, but pressures above this level can increase the risk of equipment failure or safety hazards due to increased stress on the boiler and associated components.

At 15 psi, systems can effectively provide the necessary heat without exceeding safety standards. This pressure is generally sufficient for achieving a comfortable heating output in residential applications, while also complying with most industry regulations. Adherence to this pressure limit helps protect both the integrity of the boiler and the safety of the occupants within the building. Understanding this threshold aids HVAC professionals in the proper installation, maintenance, and operation of steam heating systems.