Inside a clever Honeywell boiler wiring centre and a 3-way valve.

This unit is pure, simple genius. It's been around for a long time and has taken the complexity of wiring up traditional heating systems away completely, by providing a clearly marked set of terminals that results in very easy and neat wiring of heating systems.
The simplicity hides the fact that someone basically solved a complex wiring puzzle that allows well spaced connectors to be mounted on a simple single sided PCB. I bet they spent a lot of time doodling on a notepad and trying lots of combinations until they got it perfect.
It reminds me of a custom wiring PCB used by Unusual Rigging in a Disney attraction - that simplified wiring of computer controlled hoists, and also gave a lot of useful diagnostic indicator LEDs and test points for troubleshooting.

In the video I also dismantle and reverse engineer a three way valve as used with the wiring centre to show why it simplified the connections in a system that cut component costs by achieving a lot with a small number of components using devious trickery.

For more info on these systems, check out John Wards video on the Y-plan wiring system:-
   • Central Heating Electrical Wiring - P...  
John also has other videos covering the wiring of different heating systems.

The Honeywell wiring centre should prove an inspiration for use of custom marshalling PCBs in other applications. It's a simple concept that saves a lot of time when wiring equipment, and allows for easier troubleshooting and onboard diagnostics. (LEDs to confirm presence of power rails, show signals and indicate tripped protective devices.)

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