After 10 years of use I had to replace the domestic hot water plate to plate heat exchanger in my Sanier Duval ThemaClassic Combination 24E Boiler (because the boiler started to indicate overpressure). The process is quiet simple, had to unscrew and remove a few screws securing it onto pump mounting and 3-way valve/bypass housing. Then, remove the original plate to plate heat exchanger from boiler and fit replacement heat exchanger (SWEP made, good product). Works seamlessly since then.