North American hydronic professionals can now choose from dozens of modulating/condensing (mod/con) boilers. Many are designed for wall-mounting. Those who design these boilers strive for small enclosures and low weight. After all, who can’t appreciate a boiler that one installer can lift onto wall brackets, compared to the struggle required to move a 400-lb. boiler down a set of basement stairs?
To make boilers small and light, the heat exchanger in them has to be small and light. This can be done several ways using materials such as stainless steel, aluminum and copper. The results can be impressive. Imagine a heat exchanger that can move 100,000 Btu/hr. from combustion gases to water, while weighing only a few pounds and taking up less space than some of those three-ring product information binders sitting on your office shelves.