Vortex Eco boiler with built-in stainless steel heat exchanger and turbulator baffle system. Max. Central Heating Output: 21kW Stainless Steel Heat Exchanger Top, Side or Rear Flue Outlet Cylinder Compatibility Dependant on System Compatible with Solar Panels 2 Year Manufacturers Guarantee (Registration Required, T&Cs Apply) 50,000-70,000BTU Without Display Max. Central Heating Output: 21kW Stainless Steel Heat Exchanger Top, Side or Rear Flue Outlet Cylinder Compatibility Dependant on System Compatible with Solar Panels 2 Year Manufacturers Guarantee (Registration Required, T&Cs Apply) 50,000-70,000BTU Without Display