The high-efficiency boilers of Mark The Mark High-efficiency boilers are very compact, sustainable and available in 4 different models: ECOFLEX (capacities: 168 kW, 210 kW, 252 kW and 294 kW) POWERFLEX (capacities: 340 kW up to 600 kW) MEGAFLEX (capacities: 850 kW and 1020 kW) MAXIFLEX (capacities: 2200 kW) The Mark boilers are a.o. suitable to heat offices, garages, warehouses, apartment buildings, workshops, distribution centers and showrooms. For a complete heating solution from Mark it is also possible to combine the Mark boilers with water-supplied products such as the TANNER MDA and INFRA AQUA ECO.