Octaveblue - John Turnbull

These pages show the schematic wiring for the very popular Honeywell Y-Plan and S-Plan fully pumped central heating systems. The diagrams are animated to show the path taken to operate the various components in each mode of operation.

Select the appropriate mode to see the diagram.

Y-Plan
Hot water only
Central Heating only

Hot Water and Central Heating
Both calling
HW satisfied, CH calling
HW calling, CH satisfied
Both satisfied

S-Plan
Hot Water calling
Central Heating calling

For an explanation of AC (Alternating Current) and the Flame Rectification Flame Failure Device (FFD) click here

Please note that all information on this web site is provided 'as is' . Whilst every effort has been made to ensure its accuracy, no responsibility can be accepted for any damage, loss or other misadventure as a result of its use.

You should NEVER work on a gas appliance unless you are Gas Safe registered.