The GTB Series of hot water boilers is a unique three pass, horizontal fire tube, water-backed boiler design developed and perfected in Switzerland and is a standard in the EU community. This particular shell design overcomes thermal shock problems common to other multi-pass boilers. Thermal stress is greatly reduced because of two unique features of the furnace. Firstly, the larger diameter, shorter furnace produces less thermal expansion than a furnace of an ordinary boiler. Secondly, the furnace end is supported by stays which are attached to the rear tube sheet. Tube sheet fatigue failures are eliminated because shear stress between the furnace and the rear tube sheet is greatly reduced.
Greatly reduced footprint given relatively large diameter and short furnace design