How does the heating system come on? Most domestic houses in the UK have one of two heating control systems. Both are designed to closely control your heating system.
Here we talk about the ‘Y ’ plan. In the past this was by far the most common setup, as it only requires one valve. Y-Plan heating systems were widely used in older heating systems.
It can still be fitted today, however is not suitable for systems with more than one heating zone. Port Valve Operation. These two valves can be independently controlled and switched, as seen in the example below.
It is used mostly on vented heating systems with hot water cylinder fed by a cold water storage cistern. What is happening when HW is called for there is a loud bang from the 3way valve.