Open Vented Central Heating System Diagram

Open vented system layout.

Open vented central heating system diagram.

The open vented system is fed from a feed and expansion tank located in the loft this keeps the system topped up and also allows the water to expand as it heats up. An automatic bypass valve is fitted inside most combi boilers by the manufacturer these days. Central heating systems are either open vented or sealed systems. Open vented central heating system.

No external pump no tanks no external expansion vessel no motorised valves and in many cases item 6 is not needed either. The diagrams below show three central heating types. You will find a draincock usually situated on the return pipe blue in our diagram which is used to drain the water from the system. This diagram illustrates how simple the heating system connected to a combi boiler is.

Fitting the components together to make central heating systems central heating systems come in generally three combinations. System boilers are slowly becoming more common. The vented boiler regular boiler and combination boiler systems probably account for over 95 of water based central heating installations. You will need a rubber hose long enough to reach an outside drain from the draincock.

Nb not to be confused with vented and unvented hot water tanks which are explained in our guide to hot water cylinders many homes in the uk still have an open vented heating system and in some cases they are the better option for your home.