IBO ITALY DHW expansion vessels are diaphragm pressure vessels used in domestic hot water systems to stabilize pressure and compensate for the thermal expansion of water. They have a blue outer coating and are designed for operation in closed water systems within a temperature range of approximately -10 to 100 °C (for short periods, up to 130 °C, max. 2 hours).
Purpose and operating principle
- The vessel absorbs the excess water volume generated during heating, limiting pressure increases in the DHW system and protecting the fittings and safety valve from frequent activation.
- The inside of the tank is divided by a flexible diaphragm into a water side and a gas side; an increase in pressure on the water side compresses the gas cushion and gently equalizes the pressure in the system.
Operating conditions and pressure
- The vessels are designed for pressures of up to 25 bar, which should be treated as a limit value—a permissible short-term load; in practice, the system operating pressure and safety valve setting should be significantly lower.
- The tanks are suitable for the typical operating temperature range of DHW systems: from sub-zero installation temperatures to approximately 100 °C, with short-term increases in the medium temperature up to 130 °C permitted, corresponding to the resistance of standard EPDM diaphragms used in this type of equipment.
Construction and design
- IBO ITALY DHW expansion vessels are steel pressure tanks covered with a durable blue paint coating that protects against corrosion under typical operating conditions in indoor installations.
- As standard, they have threaded connections (3/4" or 1") for connection to safety groups or DHW systems, and the replaceable diaphragm is suitable for contact with domestic water in accordance with the requirements for diaphragm vessels used with drinking water.
