DIY Central Heating

There are two types of central heating system. The most popular form is the two pipe open-vented system in which water is heated by a boiler and pumped through small bore pipes to radiators where the heat from the water is released into the rooms. The water then circulates back to the boiler for reheating. The control of this system can be very flexible. Thermostats and valves allow the output of the individual heat emitters to be adjusted automatically and parts of the system can be shut down when rooms are not used.

A sealed system is an alternative to the traditional open-vented system. Water is fed into the system via a filling loop which is temporarily connected to the mains. The loop incorporated a non-return valve to prevent contaminating the mains drinking water. A pressure vessel heats the water in the system. A sealed system offers certain advantages over an open system. There is less likelihood of corrosion and as the system runs at a higher temperature the radiators can be smaller. There is also no need for a feed tank in the loft because pressure is supplied by the mains. This means you can have radiators in the loft.