Sealed and Vented C H Systems

A good example of one of these systems is what is known as a combi or combination boiler in which the temporary filling hose used to fill the system is always removed so it will not become a point of entry for any chemical solutions like cleaners. This is a requirement of the water authority so that it will not form a issue with contamination. The hose must be removed completely and not just turned off whilst still remaining connected. So, a sealed CH system is one that is initially filled with water and then as the name implies, sealed off, trapping the water in the pipework. The system is usually filled via a cold water mains supply connected with a temporary hose and then shut off. This water stays in the system, so is not affected by any kind of outside pressure. Leytonstone Plumbers service and repair these systems on a regular basis. Some safety functions are below:

Expansion relief valve for expansion vessel failure.

Non-return valve to prevent backflow of hot water to the cold water line.

Heat limit valve to prevent serious increase in operating temperature.

Relief valve in case system pressure rises increases higher normal running pressure.

Vented CH system.

The above system above, is sealed and therefore not affected by outside influences and is said to be in a closed loop. A vented system, however, has a water tank that is normally situated in the loft or roof space. This provides control of the volume of water in the system. The tank compensates for things like evaporation or leaks etc. It does this with the use of something called a float valve sat in a ‘feed and expansion tank’. A Leytonstone Plumber is trained to work on both systems.






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