A little help needed figuring out my system...

[andusbeckus]

Hi, I have a nest thermostat and heatlink that I would like to install and I am comfortable doing that once I know what’s what.

The main problem I have is that I want to hardwire the thermostat in so need to use the old cable linked directly to the heatlink.

This will mean I either install the heatlink next to the old programmer or next to the junction box in the airing cupboard.

Pictures included below...

 

[breadnbutter]

in my opinion best get someone out, unvented registered engineer, as the wiring will be also for the safety cut out from the unvented cylinder. which is to shut the hot water zone valve to stop heat from boiler heating up cylinder in an over heat situation.

 

[andusbeckus]

I hoping not to do that and would rather give it a go myself

 

[breadnbutter]

the cable coming from the cylinder into the junction box , the blue wire that's wired to the brown is the cut off to the hot water zone valve to cylinder. by the looks off it, don't mess that one up.