Nest Gen 3 Learning Thermostat Installation

[egasso 10]

Hello guys! just got a question here. So i have home heating system, Drayton Lifestyle LP111 timeswitch, Vaillant ecotec pro boiler and some chinese knock off wifi "smart"-ish thermostat. The "smartish" thermostat works as automatic switch (duh) when temperature drops below set temperature by 2 degrees it will turn the boiler on, simple deal, three cables in. Now, I won at work the Nest 3rd generation learning thermostat. It has thermostat which is a smart thingie with a round lcd screen, and something called "nest heat-link". I'm a bit lost here. SO cables that goes to thermostat, do they possibly come from timeswitch (which would make them 240v effectively frying the nest thermostat). Overall I'm a bit confused. I'm electrician and IT engineer of 17 years but this got me a bit confused. Anyones familiar with wiring diagrams of these things?. Thanks

[ianparkin 11]

I have installed many of these and a 3rd gen one last week

remove your existing time  clock and thermostat (If fitted)

you leave the boiler powered at all times

The heat link is powered by mains supply....

then another  pair from the heat link goes to boiler to fire  it up these are just a set of relay contacts NO which close when thermostat is calling for heat

the nest itself can either be wireless or wired

if wireless it needs powering by a usb power supply

if wired just a 2 core from heat link to nest

Edited December 11, 2019 by ianparkin

[egasso 10]

On 11/12/2019 at 10:00, ianparkin said:

I have installed many of these and a 3rd gen one last week

remove your existing time  clock and thermostat (If fitted)

you leave the boiler powered at all times

The heat link is powered by mains supply....

then another  pair from the heat link goes to boiler to fire  it up these are just a set of relay contacts NO which close when thermostat is calling for heat

the nest itself can either be wireless or wired

if wireless it needs powering by a usb power supply

if wired just a 2 core from heat link to nest

Because everything was working on 240v and I am NOT a lightbulb, I turned the power off completely. Cut the wire that went to timeswitch. check which colours goes here and there. Connected positive and negative wires, as well as pridged positive to heatlinks connection 2, and connected call for heat cable to connector 3. Works wonders, I thought it will be a bit more difficult but everything works in a sense of automatic light switch-like. Thanks for answer tho!