Hive Dual Channel - advice please

[SimSim100]

Hi...
A while ago I received good advice on here regarding the wiring up of a single channel Hive system. All went well, thanks.

Anyway, I have now inherited an old house with a Greenstar Ri boiler (Hot water & CH). There's a timer control on the wall next to it for the CH & HW and also a thermostat not too far away.

I'm sure it's been answered on here before but perhaps someone might advise of the best way to eliminate the old thermostat (without just setting it up to max). I want to get rid of it from the wall and link out whatever back at the boiler or timer.

Here are the photos of what I have.... as well as a file photo of the dual channel hive backplate.

I think my question is.... Does the thermostat wire need removing somewhere at the actual boiler and a link making there? I think I'm ok with swapping everything else.

Thanks

 

[RandomGrinch]

It appears the connections to the thermostat have been made elsewhere.
Have you come across a separate "wiring centre", or had a look inside the massive back box behind the FCU, for some hidden connections?

 

[SimSim100]

It appears the connections to the thermostat have been made elsewhere.
Have you come across a separate "wiring centre", or had a look inside the massive back box behind the FCU, for some hidden connections?

Not yet. Perhaps I'll have a peek when I'm next at the house.

 

[CBW]

As per @RandomGrinch, you should have a wiring center somewhere if you have an ri, because you’ll have an S plan.

 

[SimSim100]

I've never seen so many wires packed into a fused spur. The faceplate burst off when I undid the screws! Might the thermostat wire be one of the incoming from the above trunking?

 

[RandomGrinch]

I've never seen so many wires packed into a fused spur. The faceplate burst off when I undid the screws! Might the thermostat wire be one of the incoming from the above trunking?

Ok, blimey!

It is difficult to tell from the picture, but what we are looking for is a 3 core and earth cable, that's connected to your thermostat; this connection may be made here, or it's still possible that the connection is in a wiring centre that we haven't seen yet.

The wire colours are brown, black and grey (and an oversleeved earth).

The black wire has been oversleeved blue at the thermostat, so this may be connected to the Load N of the FCU.
The brown may be connected to the (EDIT - specific to S-Plan) call for heat from the programmer.

We then need to find whatever the grey cable (probably oversleeved brown) is connected to - this will be the connection that needs to be bridged out, probably straight to the programmer.

However, before you do any rewiring, see if you can find this cable - if you can get a helper to wiggle the cable from the thermostat side, you may get an idea of which one it is.
If you can't find it and haven't got any test equipment, it may be time to get some help!

...taking the top off of the trunking may give you an idea of where the cables go?

 

[SimSim100]

Thanks. I'll return later with more tools and my old Fluke

 

[CBW]

Crikey, looks like a wiring center!

 

[SimSim100]

I've just been to the house for further investigations. Anyway, with some long cables and an old fluke I managed to check for continuity between the thermostat wires and the wires in the FCU. Bingo - The grey (sheathed brown) switch wire at the thermostat is definitely the grey wire in the photo here. This was coupled with the black wire that goes directly to the boiler.

So... do you think I'll be ok connecting the this black wire to the live in the FCU and then also disconnecting and cutting off the live and neutral wires that go back to the thermostat? I checked those 2 as well (continuity) so I know which ones they are.

I'll then be able to install my dual channel hive too?

Thanks

PS... I think the other incoming wires at the top right of the FCU are something to do with the kitchen underfloor heating. But I'm yet to get onto that!

 

[RandomGrinch]

I was expecting the grey wire to be a link through to the controller.
It seems I guessed the wrong way around!
If the grey wire links to the black and goes straight to the boiler, then we need to know what is connected to the brown wire from the thermostat - I believe that may be a blue wire (sleeved brown) from the controller.
Whatever it may be, the wire that was connected to the brown from the thermostat needs to be connected to the black wire that goes to the boiler.

I hope that makes sense!

But then, yes, the old thermostat cable can be removed.

And great work so far!

 

[SimSim100]

Thanks. I'll report back further tomorrow when I'm there.

 

[SimSim100]

So…I’ve just been back to the house and the cable from the thermostat to the FCU is wired thus:

• Black wire (sheathed blue) at Neutral in the Thermostat goes to Black (sheathed blue) into the FCU load.
• 
  
• Brown wire at Live in the Thermostat goes to Brown FCU load.
• 
  
• The Grey wire (sheathed brown) at the thermostat goes to the chocolate block (in the FCU) connection to the black wire that goes to the boiler.

 

[RandomGrinch]

Ok then, right first time!
Connect the black (boiler) wire to the brown load at the FCU and see what happens.
The controller may be connected elsewhere.
Before attempting to change the wiring for the Hive, it's well worth putting the old controller back and checking that the system still works as intended.

Good luck

 

[SimSim100]

Ok then, right first time!
Connect the black (boiler) wire to the brown load at the FCU and see what happens.
The controller may be connected elsewhere.
Before attempting to change the wiring for the Hive, it's well worth putting the old controller back and checking that the system still works as intended.

Good luck

Many thanks. You've probably saved me quite a few quid. Cheers

 

[SimSim100]

Ohhh.. one further thing perhaps.... Is there any way I can get some bigger box/FCU such that I might be able to get all the cables back in a little easier?