Vaillant Diverter Valve – Refurbished | Part No. 178978

The diverter valve is one of the most commonly replaced components on Vaillant combi boilers, and for good reason — it is in constant operation every time the boiler switches between central heating and domestic hot water demand. Over time, the internal rubber seals degrade, the valve spindle can seize due to limescale or corrosion, and the actuator motor loses the torque needed to reliably move the valve between positions. When this happens, the boiler typically presents with no hot water, no heating, or erratic switching between modes. The Vaillant Diverter Valve (Part No. 178978) is the correct OEM replacement for restoring full combi boiler operation across the compatible ecoTEC range.

This is a professionally refurbished genuine Vaillant diverter valve. Each valve body is fully disassembled — all internal seals, O-rings, and the rubber diaphragm or spindle seal are inspected and replaced as required. The valve is then reassembled, pressure-tested for leak integrity, and function-cycled through multiple actuation sequences to verify smooth, positive switching in both directions before dispatch. You receive full OEM-spec performance and durability at a meaningful saving over a new replacement part.

Compatible Boiler Models

OEM Quality. Proven Performance. Backed by Warranty.

Every refurbished Vaillant diverter valve we supply is pressure-tested and cycle-verified before dispatch. This 178978 valve restores positive, reliable switching between CH and DHW modes on the ecoTEC Plus and Pro range, eliminating the stuck-valve, no-hot-water, and mode-switching faults caused by a deteriorated original. Supplied with a full 12-month warranty.

Delivery & Returns

Orders placed before 1:00 PM (Mon–Fri) are dispatched the same working day, with standard (2–3 working days), next-day, and Saturday delivery options available at checkout. Returns are accepted within 30 days, provided the item is unused and in its original packaging.

Note: Please confirm that part number 178978 matches your existing valve before ordering. Installation must be carried out by a Gas Safe registered engineer to ensure safety compliance and warranty validity.