Zilmet Expansion Vessel 25L

3/4" MSP Carbon Steel Height: 415mm Diameter: 324mm

The Glow-worm Expansion Vessel (Part No. 0020020744) is a genuine OEM replacement component designed to maintain stable pressure in Glow-worm sealed heating systems. This high-performance vessel absorbs excess water pressure caused by thermal expansion during boiler operation, helping to prevent system damage and maintain safe, efficient performance.

Manufactured to Glow-worm’s original engineering standards, this expansion vessel features a durable steel body with a high-quality diaphragm membrane that separates air and water chambers. This ensures long-lasting reliability, consistent pressure control, and protection for pumps, valves, and heat exchangers.

Key Features

• Genuine Glow-worm expansion vessel – Part No. 0020020744

• Designed for Glow-worm condensing boilers

• Maintains system pressure in sealed central heating circuits

• Prevents pressure fluctuations and discharge valve activation

• Made from high-grade steel with internal rubber diaphragm

• Pre-charged for easy installation and optimal performance

• OEM-quality replacement ensuring perfect compatibility and long service life

• Suitable for domestic and light commercial systems

Compatibility

• Fits a range of Glow-worm Energy, Betacom, Ultimate, and Easicom boiler models

• Also compatible with certain Vaillant Group appliances using equivalent internal components

• Designed for sealed system central heating boilers

When to Replace

• If boiler pressure drops frequently or pressure relief valve discharges

• When the existing vessel is waterlogged or fails to hold air charge

• During boiler servicing or pressure fault diagnosis

Technical Specifications

• Manufacturer: Glow-worm

• Part Number: 0020020744

• Component Type: Heating expansion vessel

• Material: Steel with rubber diaphragm membrane

• Max Pressure: 3 bar

• Pre-Charge Pressure: 0.75 bar (factory set)

• Function: Absorbs thermal expansion and maintains pressure balance

• Application: Sealed Glow-worm heating systems