Vaillant Ecotec Plus 637 / 837 / 937 Main Heat Exchanger (7 Coil) – Refurbished | Part No. 20025040

Reduced heating output, poor energy efficiency, or unusual boiler behaviour in a Vaillant Ecotec Plus 637, 837, or 937 boiler is very commonly caused by a failing main heat exchanger. The Vaillant Ecotec Plus Main Heat Exchanger 20025040 (7 Coil) is a fully refurbished genuine Vaillant replacement that restores efficient heat transfer from the burner to the central heating circuit, returning your large-output Ecotec Plus boiler to reliable, high-efficiency performance.

This is a fully refurbished original Vaillant part, quality-tested before dispatch. The 7-coil design is the factory specification for the Ecotec Plus 637, 837, and 937 models, ensuring a direct like-for-like fit. Only 1 unit remaining in stock.

Compatible Boiler Models

Key Features

• Vaillant part number 20025040 — 7-coil main heat exchanger, direct OEM replacement
• Fully refurbished and quality-tested before dispatch
• Fits Vaillant Ecotec Plus 637, 837 (R1 & R3), and 937 (2006–2012)
• Restores efficient heat transfer and resolves reduced heating output
• Only 1 left in stock — order promptly to avoid disappointment
• 12-month warranty included

Delivery & Returns

Orders placed before 1:00 PM (Monday–Friday) are dispatched the same working day. Standard and next-day delivery options available at checkout. Next-day orders placed on Fridays arrive Monday — select Saturday delivery at checkout for weekend delivery. Returns accepted within 30 days if unused and in original packaging.

Note: Installation must be carried out by a Gas Safe registered engineer.