Inside the Boiler: Multi-Pass vs. Single-Pass Heat Exchangers! #plumber #plumbing #Boiler Just had a fascinating visit to Biasi Boilers today, and we got a close look at heat exchangers – crucial components inside your boiler! First up, we saw the multi-pass heat exchanger (a style you'll find in many boilers, including some current ones from brands like Vaillant and Baxi). These have multiple coils, and while they're effective, they can be prone to blockages on dirty systems. If one coil blocks