General description The Comet Electric Combination Boiler provides the comfort and convenience of wet central heating and domestic hot water for homes without access to mains gas. This fully controllable packaged unit is designed for 24/7 operation and is housed in an elegant enclosure. It is available in various outputs, including 9kW, 12kW, and 14.4kW, and comes with a 140 Litre Duplex Stainless Steel Hot Water Cylinder.