What have I done wrong wiring up this boiler thermostat?

anthonyseoul1 · 29 Nov 2021

Hi all,

I am connecting a wireless thermostat receiver to my boiler but it isn't working correctly when it comes to the central heating and I'm not sure where I am going wrong. I've done a similar boiler before but this one is puzzling me.

The boiler is a Biasi Riva Plus HE.

The hot water side is working fine.

When I turn up the thermostat dial to turn on the heating, the receiver clicks and the green light comes on. However, the boiler doesn't kick in to turn on the heating. The boiler was working fine before when it was just wired into the spur with the external controls linked with a piece of cable.

I'm wondering if I need to tinker with the boiler controls on the boiler itself to switch it to thermostat mode or something? Nothing like this is mentioned in the instructions booklet.

Here are a few pictures of how I've wired it:

This is the wireless receiver. The L and N are piggybacked from the mains to the boiler. L1 and LX come from the external controls side of the boiler.

This is the mains to the boiler. One cable is from the fused spur, the other goes to the receiver.

This is the external controls in the boiler. These go to L1 and LX in the receiver.

stem · 29 Nov 2021

The wiring looks to be correct. Power from L E N, and thermostat contact to 3 & 1

Is there an existing timeswitch somewhere? Perhaps part of the boiler? If so that should be set to be permanently on, assuming of course that your new Siemens thermostat is of the programmable type and incorporates both time and temperature control in one unit.

Taylortwocities · 29 Nov 2021

If you take the wires off L1 and Lx on the receiver, snd connect them together, does the boiler fire up then?

Steve · 29 Nov 2021

Are there any other devices connected? An old programmer or stat? Are you able to trace the entire cable from the boiler to the receiver? As suggested, temporarily link the control wires and see if the boiler fires up.

Old Salt · 29 Nov 2021

I am not an electrician or boiler dude but the last picture shows brown and blue connected to each other via the chocolate block (black outer cable)?

Taylortwocities · 29 Nov 2021

Old Salt said:
I am not an electrician or boiler dude but the last picture shows brown and blue connected to each other via the chocolate block (black outer cable)?

It doesn’t matter in this application. Blue and brown are just colours, the stat connection to the boiler is what is known as “volt free”. The label on the boiler tells you that.

EFLImpudence · 30 Nov 2021

Old Salt said:
I am not an electrician or boiler dude but the last picture shows brown and blue connected to each other via the chocolate block (black outer cable)?

So does the previous picture.

anthonyseoul1 · 30 Nov 2021

Thanks everyone for your input. I managed to get this working.

As stem suggested, the boiler itself has a digital time switch which needs to be set to permanently on.

I appreciate everyone's help

Old Salt · 30 Nov 2021

Taylortwocities said:
It doesn’t matter in this application. Blue and brown are just colours, the stat connection to the boiler is what is known as “volt free”. The label on the boiler tells you that.

Fair enough but made me wonder and to be frank scared the sh*t out of me

SUNRAY · 30 Nov 2021

stem said:
The wiring looks to be correct. Power from L E N, and thermostat contact to 3 & 1

View attachment 252584

Is there an existing timeswitch somewhere? Perhaps part of the boiler? If so that should be set to be permanently on, assuming of course that your new Siemens thermostat is of the programmable type and incorporates both time and temperature control in one unit.

except it's wired N E L and not L E N as indicated by the mismatch of wiring colours and the shown wiring installation note.

SUNRAY · 30 Nov 2021

Old Salt said:
Fair enough but made me wonder and to be frank scared the sh*t out of me

I admit my first reaction when seeing the pic was

, I made the guess the blue was likely to be neutral for the thermostat heater.
In my opinion a silly selection of wire colors within the boiler.

333rocky333 · 1 Dec 2021

stem said:

The wiring looks to be correct.

Click to expand...

Is this connected right

stem · 1 Dec 2021

Indeed! sorry folks don't know how I missed that

either need to go to spec savers, or stop looking at the pics on my phone.

I looked at the top connections to see that the new thermostat was connected to the incoming 230V supply correctly which is is. It's the original boiler connection that's wrong.

@anthonyseoul1 you need to rectify that.

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What have I done wrong wiring up this boiler thermostat?

anthonyseoul1

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