We always fit s plans now regardless easier to wire simpler in design. The s plan is popular because it is versatile you can add an unlimited number of zones simple to wire and easy to fault find on.
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S plan wiring diagram with unvented cylinder. Heating control ntc cylinder sensor connect timer to the no dhw demand nc no dhw e orange grey 2. This diagram shows the wiring layout using the most typical components. S plan heating systems are now the most common type of system installed in the uk after combination boiler systems which do not have any external motorised valves. Output from the normal cylinder thermostat is connected to the high limit thermostat and the output from that powers the 2 port valve motor. Generally only used when installing an unvented cylinder to an existing y plan system. X range x plan wiring diagram unvented cylinder option gyellow cut off dhw sl coil.
As said though the unvented cylinder needs to have its own zone valve so you would be better off using an s plan. Part 2 in the series looks at s plan wiring a system which uses two separate valves. These are shown at the bottom right of the diagram. This video covers the wiring and electrical operation of an s plan system with two 2 port valves. Central heating electrical wiring part 2 s plan. For new installations s plan is a far better choice.
Orange grey wires from ch zone are not required please isolate opentherm make safe. Wiring diagrams and further information continues below. Here coloured wires indicate the permanent mains supply to the boiler and programmer. Also you could use your existing combi to run an s plan no need for a replacement boiler if the existing is sound. One valve for hot water another for heating. Electrical wiring for central heating systems.
Wiring is based on the standard y plan with the addition of a high limit thermostat and a 2 port motorised valve.
Gallery of S Plan Wiring Diagram With Unvented Cylinder
