Honeywell st699 to st9400c wiring

[Calliman12]

Hello I have a question switching the above central programmers. I seem have a few more wires than other examples I’ve seen online.

For instance I have 3 wires in terminal 1 (brown and 2 red: one is a bridge to terminal 5 which I believe would be discarded); also have 3 wires into terminal 2 ( 2 blue and 1 black). This setup seems to have more wires than other examples. Can anybody guide me on how to switch over to the st9400c?

Thanks in advance.

 

[Calliman12]

Photo of current wiring attached.

 

[freddo]

The st9400c installation manual has a terminal by terminal replacement guide chart for swapping a 699 to a 9400c
It's available here if you don't have it in the box for some reason.

If an existing terminal has more than 1 wire all those wires must go in the new terminal (except the links in terminals 5 and 8 as they are internal in the 9400c)

 

[brianmoooore]

The original wiring is all 'old' colours, including one of the blues, which is part of a red/blue/yellow cable.
There appears to have been a 'new' colour wire added at some time - a blue/brown flex, which may or may not be a bodge, so proceed with caution.
There's also no sign of any earth wires in your pic. Unless the wiring is really old, each of the cables should have one, and they must all be connected together..

 

[freddo]

The old unit appears to be fitted to a flushed in back box so hopefully the earths are connected to the earth terminal there.

 

[brianmoooore]

Hope full y.
................

 

[Calliman12]

The st9400c installation manual has a terminal by terminal replacement guide chart for swapping a 699 to a 9400c
It's available here if you don't have it in the box for some reason.

If an existing terminal has more than 1 wire all those wires must go in the new terminal (except the links in terminals 5 and 8 as they are internal in the 9400c)

Thanks, any terminal with more than 1 wire went into new terminals. Fitted and working. Thanks.

 

[brianmoooore]

Any idea what the blue/brown flex is for? Working is not necessarily safe!

 

[freddo]

Power cable from the central heating fused spur, or boiler supply flex?