How many safety valves are required for a boiler with over 500 square feet of heating surface?

For a boiler with over 500 square feet of heating surface, the requirement stipulates that at least two safety valves must be provided. This requirement is based on safety considerations; having multiple safety valves ensures that, in the event one valve fails or is unable to function correctly, the other valve can still operate to release pressure and prevent dangerous situations such as boiler rupture or explosion.

Additionally, the specific regulations and codes governing boiler operation often dictate that the safety measures should be proportionate to the size and pressure of the boiler. In this case, with a heating surface exceeding 500 square feet, the need for redundancy in safety systems is crucial to maintain an operational safety margin, thus necessitating the installation of two safety valves. This arrangement not only complies with legal requirements but also promotes operational integrity and safety in boiler operations.