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:-
https://www.youtube.com/watch?v=B7eAiiKUk2Y
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.)
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
http://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.
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:-
https://www.youtube.com/watch?v=B7eAiiKUk2Y
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.)
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
http://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.
I have this in my house, with a Landis & Gyr RWB2 mechanical timer controller. That also lives on in the Siemens RWB2e which has the exactly same wiring diagram in the manual as on the back of my unit. As a hint of age, the PCB of the honeywell sundial has 1987 stamped on it for when it was designed (pre RoHS of course which seems to have been the big change to your current unit), and the date of manufacture of the rwb2 was 1996.
What's going to happen if you remove the diode? 🤔 Or the diode is not conducive?
I work in HVAC field and we have diverter valves on individual duct coils that work on a return loop to a boiler.
The 24v vac mains, the valves modulate 0-10 VDC sig. voltage
Thanks to this video I have determined my 3 port valve has an issue with the spring return, I have none!
The motor works and the CH and HW can be heated etc but because there is no spring return anymore manual override can not be engaged and the valve can get in a configuration where it directs water the wrong way.
In our system, the three way valve and the boiler thermostat both link directly into the furnace connection blocks, as does the outside temperature sensor and the room unit (behind a Bosch proprietary protocol). Things like boiler thermals and power level settings are all on the furnace lcd display.
hi can i use this on a combi boiler with UFH manifold
I have Honeywell V4073A 3 port valve and it works almost the same but documentation says if 240V in grey wire = Valve held in last position but if last position was CH, approx 100V output on orange wire. I don't understand why ~100V present on the orange wire and what is the purpose of it?
Funnily enough I just changed one for my dad a couple of days ago, his was a honeywell but it looked nothing like that one inside. Bought a Corgi version instead at half the price and it was identical to the honeywell I removed.
Another oddity I've noticed with these mid position valves – they only seem to fail on a Sunday evening, just after toolstation and screwfix have closed. I've got to be in work early in the morning, and will be away for a few days. So the boss is left without heating or hot water until I get back. Ought to start keeping spares on the shelf!
send the Honeywell to jw
This would be a formidable place to have a stepper motor and a feedback potentiometer…… you could provide hot water at the rate you want, whenever you want, on demand, with ultra fine control….
This is probably one the best video's I've seen on YouTube ; thank you for taking the time to explain
Gotta be honest. I've never liked these due to the implementation. Those links that you cut are usually connected to 240v line. That means if your poking around in there fault finding, there are sharp, spikey and very live wires with thier ends exposed waiting for you to accidently poke. A better way to do it would be dual terminals for each link with a removable link wire. Either way, I use a traditional strip of terminal blocks when I wire up gravity or multi-zone systems.
Clive, you've saved the day again. I discovered your channel when attempting to diagnose a faulty cooker clock/timer, turned out to be a dry solder joint, one of your vids helped me find and fix it, and now you've helped me with my non-existent hot water! I thought I'd have to replace the whole valve, but I can do just the motor and JB?! And lo, there was again hot water! Much appreciated! What will you get me fixing next?!
Jay Wubble yew?
In the US, at least from my observation, the system is quite different. The valves and control logic runs on a 24V system, and each zone is controlled by an individual valve. Each thermostat will have both an on and off signal, and the valve will travel to the set position and then disconnect the motor. A signal wire will then run to the boiler from each valve.
+bigclivedotcom
What do you think about debugging these valves? Have a V4073A1088 here [classic honeywell valve], which has become sticky! — will fail to "roll back' on the springs reliably [i.e. won't run hot water] — even after oiling and poking in-situ gets stuck especially in the mid position (can often unstick by setting programmer CH-only and room-thermostat high, to cause valve-motor to go to full-extent, and THEN set to go back to hot-water-only "all in one go").
With head removed, can you reliably tell if the stickiness is in the actual valve itself by twibbling the actuating point by hand/tools?
Ideally want to change the head-only and not do a full system drain-down until next summer at this point…