Hive to Vokera Easi Heat + C combi boiler wiring

[T Bone]

Hi everyone,

Another Hive thread...

So I'm trying to connect a Hive thermostat to my boiler Vokera easi heat plus. Two plumbers already let me down as none of them felt confident to succeed. So be it, I'll do it myself, with your help...

Here is my homemade diagram and pictures.
I'm thinking to connect a 5 core flex wire from the Hive receiver to the boiler PCB and power
N : connect to Neutral in the boiler
L : connect to Live in the boiler
E : Does the Earth needs to connect to the boiler ?
1 : connect directly on CN5 in the boiler
3 : connect directly on CN5 in the boiler

I have many questions (and I'm not an electrician...) :
- If I connect the receiver L, N and E in the boiler, that'll double the LNE connections, right ? Is that a problem ?
- If my receiver cables go directly in CN5, what do I do with the previously light blue wires (x2) linked to CN5 ?
- The black wire from CN5, I decided to leave it as it is... Correct ?
- Any chance I blow up my boiler doing that ?

Thank you and hope we can solve that !

 

[ericmark]

Your diagram shows M2 as connection to thermostat which does seem together with on/off switch to bridge CN5 but would it not be easier to use M2? Since the wall thermostat has volt free contacts it does not really matter where it gets power from, but from the same supply as boiler is normal, an earth wire should be used but does not need to be connected with class II equipment, it just needs to be there for future use.

 

[ianmcd]

yes that is correct, you can connect the Earth if you want but it serves no purpose, take note though that the colours of the wires in your diagram for L&N are the wrong way round, dont mix them up

 

[T Bone]

Yes thanks Ian, good spot on the colors. Corrected now
I'll leave the earth unconnected then.
Ericmark, I'll have a look if I can find the M2 on the PCB but not sure it is as accessible as CN5. Also I read a few threads saying it needed to be connected to CN5, not M2 (see the Fig B - Voltage free control).

 

[ianmcd]

M2 is simply another connection in the CN5 series circuit, just connect 1@3 on the Hive to CN5 at the boiler, any way round it doesnt matter, just remove the two existing wires that are in CN5, they are now just a piece of wire and dont connect to anything, I would just leave them there just tape them up, if for some reason in the future you decide to upgrade to 230V switching you will need them

 

[ianmcd]

Since the wall thermostat has volt free contacts it does not really matter where it gets power from

Yes it does, it MUST come from the same power supply as the boiler, could be a shared fused spur, but it does matter where it gets its power from

 

[ericmark]

Yes it does, it MUST come from the same power supply as the boiler, could be a shared fused spur, but it does matter where it gets its power from

OK it says same supply, how many houses have you seen with more than one supply? Yes have seen it, but second supply is normally economy 7 or similar.

The Worcester Bosch instructions which @stem posted also say type A RCD protection. Be it a plumber swapping a RCD in a consumer unit or an electrician taking boiler covers off to check state of wiring, yes rules say we should do it, but in both cases there are problems where an electrician may remove a gas sealed cover or plumber electrocute himself playing in the consumer unit.

OK should have said ideally the supply should be from the same circuit. However even electricians it seems do not see a FCU as forming a circuit, and if there is a fuse inside the boiler then if saying same circuit it must come from inside the boiler. But you will note it does not say same circuit, it says same supply.

Yes I would agree better if from same FCU or plug as boiler, but MUST is the wrong words, desirable yes, but MUST no.

My central heating has 10 supplies, one 230 volt and 9 x 3 volt. It did until I rewired have a plug and three FCU's which I agree is silly which is why I rewired, but silly yes, illegal no.

I know the Hive wiring is historic, and comes from using same back plate for a thermostat and a programmer in the past, but using the same back plate for volt free (single channel) and non volt free (duel channel) is flawed, it is simply too easy to fit the wrong one. However getting 230 volt and 24 volt linked is not going to be stopped by using the same circuit.

 

[ianmcd]

Yes I would agree better if from same FCU or plug as boiler, but MUST is the wrong words, desirable yes, but MUST no

You better contact the boiler manufacturers then, as we have to work to their instructions not your ramblings

 

[ericmark]

You better contact the boiler manufacturers then, as we have to work to their instructions not your ramblings

No that has also been changed, the follow manufacturers instructions has been changed to take manufactures instructions into account.