Vaillant Main Heat Exchanger – Refurbished | Part No. 0020135129

The main heat exchanger is the heart of any condensing boiler — the stainless steel assembly where combustion gases give up their heat energy to the primary water circuit before passing into the flue. On a Vaillant ecoTEC boiler, a deteriorating main heat exchanger typically causes progressively worsening efficiency, frequent high-limit thermostat trips, unusual flue temperatures, or — in the case of physical failure — visible signs of water contamination in the flue path or gas odour in the primary circuit. The Vaillant Main Heat Exchanger (Part No. 0020135129) is the correct OEM replacement for restoring full thermal output, condensing efficiency, and safe operation across the compatible ecoTEC range.

This is a professionally refurbished genuine Vaillant main heat exchanger. Each unit is fully inspected — the stainless steel exchanger body, condensate collector, flow and return connections, flue manifold, and all associated gaskets and seals are examined and replaced as required. The assembly is pressure-tested at working pressure to confirm leak-free integrity across all joints and connection points before dispatch. Refurbished to full OEM specification at a meaningful saving over the cost of a new Vaillant exchanger.

Compatible Boiler Models

OEM Quality. Proven Performance. Backed by Warranty.

Every refurbished Vaillant main heat exchanger we supply is pressure-tested and performance-verified before dispatch. This 0020135129 unit restores full primary heat transfer and condensing efficiency, resolves high-limit lockout faults caused by a degraded or partially blocked exchanger, and ensures complete separation between combustion gases and the water circuit. 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 0020135129 matches your existing heat exchanger before ordering. Main heat exchanger replacement must be carried out by a Gas Safe registered engineer to ensure safety compliance and warranty validity.