Help with thermostat installation - dodgy wiring?

[Swasterix]

Hi everyone.

First time poster after a bit of advice, which would be massively appreciated! Appreciate Nest has been covered at length, but cant find anything matching my query (sorry if its been covered!!).

Ive just ordered a Nest thermostat to replace my current Drayton Digistat +3. My boiler is an Ideal Logic Combi 35. While I'm waiting for this to be delivered I thought I would take a bit of time to familiarise myself with the wiring etc.

Looking at the boiler wiring diagram, there are two connections; Room Stat and Timer
In the instructions for the Nest there are; Common and Call For Heat
In the instructions for the Drayton there are; C and On

The wiring diagrams in the boiler manual (page 27), Nest Manual (page 35) and Drayton Manual (page 4) appear to say that the connection from the Timer terminal goes to the Common terminal, and returns from the Call For Heat terminal into the Room Stat terminal.

However, my the Drayton is currently wired up in the opposite direction; Room Stat -> C, On -> Timer.

Presume the Drayton isnt wired up wrong, or I guess it wouldnt work? Am I missing something?

Thanks again!
Dan

EDIT: I've came to the realisation that although it's wired up contrary to the wiring diagram, it doesn't matter which was it is wired up, as the unit simply closes the switch and completes the circuit when there is a demand for heat. Would I be correct in this assumption? (Night shift brain, taking a little time to shift!)

 

[Swasterix]

To make things a little clearer, the below diagram might help explain things better. Thanks again

 

[stem]

I've came to the realisation that although it's wired up contrary to the wiring diagram, it doesn't matter which was it is wired up, as the unit simply closes the switch and completes the circuit when there is a demand for heat. Would I be correct in this assumption?

Yes that would be correct. Your thermostat has potential free contacts, so it doesn't matter.

You may have confused folks with your 'Actual Wiring' diagram because you have removed the permanent live from your boiler, which because it's a combi you would actually need, and your boiler terminals are called "room stat / timer" not "1 & 2"

 

[Swasterix]

Hi Stem

Thanks for the reply. The original thermostat was installed by the developer so can't be held responsible for that appreciate your help, am mid install now so fingers crossed!!

 

[G0WFV]

This is the exact same system we have in our house and am trying to see if Nest is a viable replacement for the thermostat/controller. Did it work?