Viessmann Vitodens 100-W WB1B Expansion Vessel CRI 8 – Refurbished | Part No. 7828646 7837892

The expansion vessel is the silent guardian of boiler pressure. In a sealed heating circuit, water expands as it heats — and when the vessel's diaphragm fails, there is nowhere for that pressure to go except through the relief valve. Repeated activation causes cumulative damage to seals and internal components. The Viessmann Expansion Vessel CRI 8 (Part No. 7828646  7837892) is the exact OEM replacement for the Vitodens 100-W WB1B combi and system range, restoring pressure stability and protecting your boiler investment.

This is a professionally refurbished genuine Viessmann component. Each unit is stripped, cleaned, and pressure-tested to OEM specifications before dispatch. The 8-litre CRI capacity fits directly as a like-for-like replacement — no modifications needed — enabling a clean, compliant swap.

Compatible Viessmann Models

OEM Quality. Proven Performance. Backed by Warranty.

Every refurbished vessel is inspected and pressure-tested to OEM standards before dispatch. Reduces wear on pumps and heat exchangers by preventing overpressure cycling. Supplied with a full 12-month warranty — professional-grade reliability at a fraction of new-part cost.

Delivery & Returns

Orders placed before 3:00 PM are dispatched the same working day. Standard and next working day delivery options are available at checkout. Returns accepted within 30 days, provided the item is unused and in its original condition.

Note: Please confirm that part number 7828646 matches your existing vessel before placing your order. Installation must be carried out by a Gas Safe registered engineer to ensure safety compliance and warranty validity.