Developed to reduce wasted energy this unit pre-heats the water using heat from the gas exhaust, meaning you'll use less energy. The C7 has a secondary heat exchanger which utilises the exhaust gas to help pre-heat the water. It is due to this feature that the unit doesn't need to use as much energy to heat your water to the right temperature, saving                    
                                            
                                                        Kelly Lindley —
                            A laundry and two Bathrooms done and one to go these guys are great. Awesome to work with, really good communication, friendly