* Boiler spare parts must be fitted by a certified Gas Safe engineer * Orders received before 4pm are usually dispatched for next business day delivery. This Vaillant Heat Exchanger, with the part number 0020135129, is a crucial component for your boiler system. Ensure it is installed by a qualified Gas Safe engineer for optimal performance and safety. Typically, orders placed before 4 pm are dispatched for next-day business delivery.