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 exterior coating and are designed for operation in closed water systems at temperatures from approximately -10 to 100 °C (up to 130 °C for short periods, 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 water-side pressure compresses the gas cushion, gently equalizing 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—the 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 a permissible short-term increase in medium temperature to 130 °C, 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 coated with a durable blue paint coating that protects against corrosion under typical operating conditions in indoor installations.
- As standard, they feature threaded connections (3/4" or 1") for connection to safety groups or DHW systems, while the replaceable diaphragm is suitable for contact with potable water in accordance with the requirements for diaphragm vessels used with drinking water.
