Ok, so there has been some very usefull information on this page which has led me to investigate how to get a dual channel hive working as a single channel system.
As mentioned previously, the reason why it's not a straightforward swap of wires is that a single channel receiver works as a switch between two contacts,
But the dual channel receiver works as a 240v supply from the contacts, not as a switch.
However, thankfully HIVE like to save money and the internals are almost exactly the same for both !
Just that there is two wires connected either in single mode or dual mode.
And best of all it seems only 1 single wire needs to be moved.
** DO NOT ATTEMPT THE FOLLOWING.
THIS WILL VOID ANY WARRANTY, AND IS MESSING WITH VOLTAGES.
IT IS STRONGLY RECOMMENDED THAT YOU PURCHASE THE CORRECT RECEIVER TO USE **
that said, im just going to document what i did.
Basically youre looking to do the following... View attachment 283447
And all it takes is moving 1 single wire which is currently connected to live, over to PIN 1...
View attachment 283448
this is the common of both relays currently connected to L
View attachment 283449
This is where it needs to be disconnected from L and reconnected to 1
View attachment 283450
This is the finished change.
Notice i have simply connected it to the existing wire going to pin 1.
Two reasons- keeps job simple, no need to disconnect the wire already at PIN 1, since in normal state its NC and so basically looping on its self.
And so that i could easily unsolder it and move it back to L if in the unlikely even i want to chnage it back.
So i wasn't too worried about the connection since its only going to be switching a low level 24v signal, rather than a 240 feed.
Once this is complete, you can wire the backplate to pins 1 and 3 just like on a single channel receiver. However pin 3 on dual channel is actually controlled as HOT WATER. So app, thermostate and button at front would all be wrong.
So its better to.connect backplate wiring to PIN 4, which is controlled as CH.
Just be sure you leave yourself a little message tucked behind the hive receiver explaining what you have done, and why pin 4 not pin 3!!
Good thing with this is that should receiver be reconnected to a old style central heating system without changing it back, electrically its "safe" and will simply not work. No risk of damaging anything.
Again, this is not recommended to try, even though it works. And cannot be liable for any damage or injury caused.