Heating Thermostat Wiring Headache!!!

[Lyndor]

Hello everybody - please can someone help me!!

I thought it would be easy to swap my old dial thermostat for a new sparkly digital one but I'm struggling.

My old one is a Sunvic TLX 5101 with a Blue Cable in terminal 1, Red Cable in Terminal 2 and a Yellow cable in terminal 8.

The new one is a Homexpert by Honeywell THR870CUK (link to manual below)
http://www.homexpertbyhoneywell.com/Documents/EN Manuals/THR870CUK-EN-d05.pdf

I have done a lot of googling and nothing seems to explain where I should put the wires, most only seem to explain installation with 2 wires and I have 3.

PLEASE can someone help me because I'm about to be defeated by a stupid piece of plastic.

Thank you so very very much
x

 

[Dan Robinson]

Are you sure the blue wire went to terminal 1? I was under the impression it went to terminal 2.

Put your yellow wire to terminal B, and the I would NORMALLY say put the red cable to terminal A. The blue wire can then be made electrically safe.

Blue (terminal 2 on your old stat) is normally a Neutral wire and it not needed on your new thermostat. Make sure what that wire is dong before you power up.

 

[Lyndor]

Yes you're totally right the blue wire is in Terminal 2 - too many wires and too many back to front diagrams for an amatuer like me!!

So yellow to Terminal B, Red to Terminal A and make blue safe then in that case?

I will try it a little later today and let you know - you may have just made me a very happy lady!!

 

[Taylortwocities]

To the OP.
There's a guide on how to do this on the WIKI. Its the best place to look first for simple stuff like this.
Here you are......


//www.diynot.com/wiki/electrics:how_to_replace_a_room_stat

 

[Lyndor]

Thank you to everyone for your help, it is up and seems to be working.
I literally could not have done it without you - I'm sorry if my request seemed a little dumb!!!