What is required on a hot water boiler when the boiler pressure exceeds 30 psig?

When the pressure in a hot water boiler exceeds 30 psig, the installation of an expansion tank becomes crucial. The primary function of an expansion tank is to accommodate the increased volume of water that occurs as water is heated; when water heats up, it expands. Without a way to manage this expansion, it could lead to excessive pressure buildup within the system, which can damage components or create safety hazards.

An expansion tank helps maintain the system’s pressure by providing a space where the expanded water can go, thereby allowing the system to operate safely within its designed pressure limits. It is a vital part of managing thermal expansion in a hot water heating system, making it a key requirement when pressure levels exceed 30 psig.

The other listed components, while important for boiler operation and safety, do not serve the specific function related to managing pressure caused by water expansion in the same way. A pressure gauge indicates the system pressure, a water column assists in level measurement, and a blow-off valve is used for draining or releasing pressure, but none of these components specifically address the need to manage water expansion within the boiler system.