Wiring Smart Thermostat to Vokera Boiler

[Danielalford22]

Hi all I am trying to replace my Honeywell 2 core switch fed thermostat with a smart thermostat.

The new one requires both the switch cables but also constant power via Live and neutral.

Do I provide the live and neutral from the grey and blue inside the boiler and feed the switch cables from the existing red and black? (I would do all this from a 4 core cable)

Also concerned there is no earth slot in the thermostat? Is this normal?

See photos of the boiler main board and diagram of the thermostat.

Thanks in advance all

 

[CBW]

It’s a class 2 product, so no need for an Earth terminal. Yes piggyback the L (brown) and N (blue) and use the existing red and black for switching. Yes, use 4 or 5 core flex, or 3 core flex, as you already have the switching cable and wires.

 

[Murdochcat]

It’s a class 2 product, so no need for an Earth terminal. Yes piggyback the L (brown) and N (blue) and use the existing red and black for switching. Yes, use 4 or 5 core flex, or 3 core flex, as you already have the switching cable and wires.

Not 100% sure I agree with this.

On the basis it’s 230v controls, there should be a CPC in every cable. The fact that the thermostat is class 2 is largely irrelevant,

 

[CBW]

Not 100% sure I agree with this.

On the basis it’s 230v controls, there should be a CPC in every cable. The fact that the thermostat is class 2 is largely irrelevant,

Existing Honeywell won’t have an Earth terminal. Or are you saying that the earth should be connected at the boiler and ran to the thermostat and placed in a connector block?

 

[ianmcd]

be very carefull wiring that boiler with new controls, it is volt free switching if you get it wrong will be very expensie

 

[Murdochcat]

Existing Honeywell won’t have an Earth terminal. Or are you saying that the earth should be connected at the boiler and ran to the thermostat and placed in a connector block?

Yes.

All 230v cables should be connected in this way

 

[RandomGrinch]

Not 100% sure I agree with this.

On the basis it’s 230v controls, there should be a CPC in every cable. The fact that the thermostat is class 2 is largely irrelevant,

As always on the electrics forum, this has been discussed at length before!
It may depend on your definition of 'Point' and 'Accessory'.
It could be argued that the FCU is where the CPC should be terminated - there would be no issue running a 2 core cable directly to a (double insulated) appliance, from an FCU.
However, boiler controls are usually 'permanently' wired in. Again some argue that this would then come under the fixed wiring regulations.