Combi Boilers Combi boilers are designed to heat water up instantly for domestic use (e.g. shower), as well as provide heat into the central heating system. Because there is no feed tank and no storage tanks are required, the installation of Combi boilers is simple and cheap. Since there is no hot water storage cylinder, the Combi boiler eliminates the need to heat up the cylinder in order to keep it at a steady temperature for domestic hot water needs. Combi Boilers ApplicationsCombi boilers are appropriate for relatively small houses or flats, where the hot water demand is not large. The boiler is limited to the amount of hot water it can supply, and in effect when hot water is being drawn for domestic use (e.g. shower, kitchen), there is no heating going into the radiators of the central heating system. How does a Combi Boiler Work?Here is a typical description of the operation of a Combi Boiler: - Upon a signal from the room thermostat for the boiler to fire up the central heating system, the pump inside the boiler fires up. The water starts flowing passing through a narrow gap in the pipe (“venturi effect”) creating a pressure differential and causing the gas valve to open.
- Gas is ignited in the main burner
- The heat exchanger holds a limited amount of water, which is rapidly heated up, circulating around the boiler through the heat exchanger. Any expansion of the water is absorbed by the sealed expansion vessel.
- When the water temperature reaches 60c the thermostatic element expands, the hot water system valve closes and the heating system valve opens, which allows water to flow to the central heating system.
A similar operations happens upon request for domestic hot water, but rather the valves operate in opposite directions, letting the water pass through to the domestic hot water circuit rather than the central heating system. Leading UK Boiler Manufacturers Heating Central’s plumbers install a wide range of Combi boiler brands, including: - BAXI boilers
- Potterton Boilers
- Vaillant Boilers
- Worcester Bosch Boilers
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