Replacing Honeywell ST699 with Tado extension kit

[Pidea]

Hi, first time poster with relatively little knowledge of central heating controllers here !

I've got a Honeywell ST699 controller which controls a Valliant ecoTec Plus 831 combi boiler. The Honeywell is left over from when we had our old boiler and a hot water tank.

As the Valliant is a combi boiler there's no hot water to control so the Hot Water switch has always been left off.

I've taken the front panel off of the Honeywell and compared it to the images on the Tado website and there's not an exact match so I'm a little confused about which wires to move across.

This is what I have:

Working from right to left:

L: 3 red wires
N: 2 black wires
3: 1 black
4: nothing
5: red linked from L and also to 8
6: nothing
7: nothing
8: red wire linked from 8 and L

Going through the Tado website this is the nearest match:

But I don't have a wire on 6 and I have 3 on L and 2 on N.

Since I have a combi boiler and I'm not using Tado to control the hot water, am I correct in thinking that I only need to move the existing L, N and 3 across ?

Also, more from curiosity than anything else, any idea why I've got more L and N wires ?

Thanks in advance

Phil

 

[Deleted member 267285]

You need to find one that represents common, com or c and link to L and NO, normally open is your switched (3 on Honeywell). You are correct in you don’t need anything for hot water.

 

[Pidea]

Thanks, one of the live wires on the L terminal was the link so I removed that and then moved the two remaining ones across to the L terminal on the Tado. I moved the two N wires across as well and then just moved the wire from 3 to 4 on the Tado.

After turning it on and off a few times (and swapping the jumper around) it seems to be working (fingers crossed !)

Thanks for your help.

Phil