Gravity Systems: Gravity circulation is generally used in old properties to heat hot-water cylinders. It works on the principle that when heated, water expands. As a result, its weight is lesser than that of cold water. This phenomenon is advantageous because the cold, heavy water sinks down and pushes the hot water upwards. This system can be relied upon since it does not use pumps. However, it needs large-28mm pipes. Installation of the cylinder is done upstairs, on top of the boiler to give best results.

The same water is used to recirculate around the system. If the water is lost by leakage or expansion, the expansion and feed cistern makes sure there’s enough water in the system.

The vent pipe that is located on top of the cistern provides safety against excess pressure.

Pumped Systems: These are the most popular heating systems so far. The system is simple- water, heated in the boiler, is pumped round the network of pipes. It is then directed to the hot water cylinder through a motorized valve or a radiator circuit.

Sealed Systems: These heating systems are becoming more and more popular these days because of their efficiency and low cost. As the name suggests, this heating systems sealed completely and there is no feed.

A pressure container handles the water’s expansion and contraction. There’s a safety valve that relieves any extra pressure in place of a vent-pipe.

The advantage of this system is that it runs at a relatively greater temperature and hence the size of the radiators could be smaller. The loss from corrosion is also less. The pipework required is also less and no space is needed for the expansion cistern and the feed.

The disadvantage of the system is that it operates under pressure. As a result, good quality fittings are needed to make sure there are no leaks during installation.