The type THD-U classical 3 pass flame tube flue gas tube boiler with reverse
flame tube and an inner completely water cooled flue gas reversal
chamber guarantees high efficiency. The boiler consists of a cylindric
shell, the two endplates, the reverse flametube including the back flue
gas reversal chamber with water cooled finned tube wall, the dimple flue
gas tubes which increase the heat transfer (Hoval patent) and the fitting
tube, placed either on the right (standard) or on the left. The boiler door is
insulated and flue gas proof for burner mounting. The boiler is completely
electrically welded and provided with all required inspection openings.
The spacious flame tube with low thermal heat release results in an excellent
combustion and reduced emissions. The large water content gives
steady state boiler operation and thus reduces the number of boiler starts