Campini Hot Water Tank Thermostat wiring query

[gbvaliant]

IMG_4390.JPG

• gbvaliant
• 10 Oct 2023

IMG_4391.JPG

• gbvaliant
• 10 Oct 2023

IMG_4392.JPG

• gbvaliant
• 10 Oct 2023

IMG_4393.JPG

• gbvaliant
• 10 Oct 2023

I've got this thermostat in my hot water tank, and I'm trying to determine which colours are linked to Common and 1 - either blue or brown - so I can link it to a Nest thermostat and Drayton HW Valve. Earth is self explanatory.

The attached images show how it is wired currently, plus the wiring diagram on the inside of the thermostat cover.

It looks like 1 has been bridged between the regulator and the limiting device with the white cable, but then that appears to be two "C"s and no "1"??

Any suggestions as to which is the correct wire colour for Common? This is the last problem in my wiring diagram to fix - please help!

 

[Deleted member 267285]

Wiring is usually done at the wiring center, think they’re both common as the limiter also closes supply off. I’m not up on these, as they’re usually worked on by G3 registered engineers.

 

[gbvaliant]

I'm trying to connect a NEST thermostat as whoever installed the last set has left a nest of wires in a shoddy wiring centre - I'm trying to identify the C & 1 (the two wires which are red) to finish this diagram:

Nest Layout.png

• gbvaliant
• 10 Oct 2023

 

[gbvaliant]

If you assume both wires are Common, does the above circuit still work? Nest calls for hot water through 6 from the heatlink, routes through the tank thermostat through one common, back out with the other, to the switched live through the HW valve to the boiler? If tank reaches the set temperature, the circuit is broken and the boiler turns off?

 

[polesapart]

In this instance it doesn't matter. Your two diagram reds are existing brown and blue in any order.

The combined stat will give you electrical contuinity when
1) the temperature of the water that the stat reads is below stat set point and
2) the set point of the overheat safety stat has not been exceeded

Minor matter; a tag of red on each end of the blue wire would not go amiss