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Hi everyone.

Im new here and I apologise if this has already been asked.

I am trying to connect my thermostat to my existing combi boiler. The thermostat is under the boiler and has 4 core wire coming out of it. The gas engineer who came out to service the boiler said that it can't be connected as it needs a 5 core wire.

Now....

From the wall socket to the boiler, is a 3 core wire. (L/N/E) that connect to the left side of a connector block. (I apologies for not knowing the name of this part) on the right side of this block are 5 wires. L/N/E and 2 black wires. (The 2 black wires are looped on the left side of the connector block)

I know I have to unloop these and send the power from L1 / L2 (this is the terminals that are looped) to the wireless thermostat sender unit. But where do I connect the L/N/E? Do I connect it to the side of the connector block (left) which has the mains wires, or to the boiler side (right)?

Many thanks
 
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Andy-1960

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I think a bit more information is needed to enable us to comment on whether we can offer advice or recommend you seek professional help.
Make and model of the boiler, make and model of the thermostat and maybe a few photos would be a good starting point.
 
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I think a bit more information is needed to enable us to comment on whether we can offer advice or recommend you seek professional help.
Make and model of the boiler, make and model of the thermostat and maybe a few photos would be a good starting point.
I will get some photos once I get home and try and find the makes and models 👍

I have been told it will work by the engineer, but he just didn't have to correct wire is all
 

littlespark

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Don’t be tempted to use the green/yellow as anything other than an earth wire, even if it’s not required by the stat.
5 core flex is readily available from electrical wholesalers
 
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Don’t be tempted to use the green/yellow as anything other than an earth wire, even if it’s not required by the stat.
5 core flex is readily available from electrical wholesalers
Yes, I know that thank you. I am pretty good with electrics, fit all my own stuff, but due to this being my first boiler I just wanted to double check. 👍
Post automatically merged:

I will get some photos once I get home and try and find the makes and models 👍

I have been told it will work by the engineer, but he just didn't have to correct wire is all
These are the pics I could get. Hope they help. I'm just needing to know which side of the block to run the wires. Left side with mains power or right side with boiler. Also, the black wire in the thermostat sender is in L1... Does this go to live in or live out? Cheers
 

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telectrix

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looks like you need 5 core cable. L, N, E, Lin from boiler, Lout back to boiler. lookslike someone has already misused the cpc of the existing 3 core flex.
 

Andy-1960

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A 5 core flex will be required. To do this the live and neutral to your receiver need to be connected to the existing live and neutral in the boiler together with the earth conductor, then the L1 & Lx connections in the thermostat connected to the terminals that are presently linked out in the boiler (remove link!). As there is no earth terminal in the thermostat, this will need to be terminated in a connector block.
Terminate the cables on the left (the same side as the existing cables)
 
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