Gasmaster Industries Ltd. manufactures twenty-six models of high efficiency, stainless steel condensing boilers and water heaters. The nominal rating of these models is in the range of 200 8000 MBTU/hr (= 58.6 2344 kW). The heat exchangers are a series of vertical stainless steel tube coils arranged side by side with a certain distance. The volume contained between the conical sections of the coils defines the combustion chamber of the boiler. Inlet water enters each coil at the perimeter and exits at the centre adjacent to the hub. This configuration allows a counter flow heat exchange process, which contributes additional heat transfer between water and the coils.