1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Nest Thermostat to ESI 2 zone with HW cylinder

Discussion in 'Plumbing and Central Heating' started by Jessica L, 7 May 2021.

  1. Jessica L

    Jessica L

    Joined:
    7 May 2021
    Messages:
    5
    Thanks Received:
    2
    Country:
    United Kingdom
    Hello,

    I'm about to install two Nest thermostat generation 3 into a 2-zone thermostat with hot water cylinder and programmer.

    Here is the existing ESI wiring centre.

    Wiring.jpg

    I've drawn out two possible scenarios and I wanted to see if they could work.

    The black arrows are the existing wiring already in place.
    The coloured lines are the ones that I will connect.

    For both scenarios:
    -Existing wire RoomStat1 L1 to Heatlink1 T1
    -Existing wire RoomStat1 N to Heatlink1 T2
    -Connect new wire from Heatlink1 N to RoomStat1 N
    -Connect new wire from Heatlink1 L to RoomStat1 L1
    -Repeat same with RoomStat2 and Heatlink2
    -Bridge port L, #2 and #5 together on Heatlink1
    -Bridge L and #2 on Heatlink2

    Scenario 1 (Connect all to programmer)
    Remove existing wire from CH1 ON and connect new wire CH1 ON to Heatlink1 #3
    Remove existing wire from HW ON and connect new wire HW ON to Heatlink1 #6
    Remove existing wire from CH2 ON and connect new wire CH2 ON to Heatlink2 #3


    Scenario 2 (Connect to Room Stats)
    Connect existing wire from ROOM STAT1 N/O to Heatlink1 #3
    Connect existing wire from ROOM STAT2 N/O to Heatlink2 #3
    (What do I connect Heatlink1 #5 to to get the hot water?)


    Which is the best way to install this?

    Appreciate the help!
     
    Last edited: 10 May 2021
  2. Sponsored Links
  3. CBW

    CBW

    Joined:
    26 Sep 2019
    Messages:
    6,547
    Thanks Received:
    1,724
    Location:
    North
    Country:
    United Kingdom
    • Thanks Thanks x 1
  4. Jessica L

    Jessica L

    Joined:
    7 May 2021
    Messages:
    5
    Thanks Received:
    2
    Country:
    United Kingdom
    Thanks for that Chris. Yes I do know that part. If you look at the schematics, my question is just where I should get the Heat Call and HW Call. I've looked at all the threads regarding nest and ESI installations on this forum already and in regards to that thread, they only have one wire coming from the HW ON in the programmer, whereas mine has all three wires (HW ON, CH1 ON, CH2 ON) connected. I was wondering if I could use those 3 to connect into the Heatlinks terminal 5, 2 and 2 respectively.
     
    • Thanks Thanks x 1
  5. CBW

    CBW

    Joined:
    26 Sep 2019
    Messages:
    6,547
    Thanks Received:
    1,724
    Location:
    North
    Country:
    United Kingdom
    Sorry you mentioned connecting L and N from heatlinks to room stats. Yes seems logical that HW to 5 and CH1 CH2 to heatlink 1 and heatlink 2 - these are common (aka live). I’m guessing that the esi wiring centre with the soldered connections send the power to zone valves, which would be 3 and 6 respectively for heating on and hot water on (calls for heat).
     
    • Thanks Thanks x 1
  6. Jessica L

    Jessica L

    Joined:
    7 May 2021
    Messages:
    5
    Thanks Received:
    2
    Country:
    United Kingdom
    Thanks, you're suggesting to use scenario 2?

    In this case, if I remove the room thermostats that has wires L, N and N/O to replace with the nest thermostats that only uses wires L and N, what do I do with the extra wire N/O (Room Stat 1) at the wiring centre? Do I need to bridge the two terminals from N/O (Room Stat 1) to CH1 ON? And the other N/O from Room Stat 2 to CH2 ON?
     
  7. CBW

    CBW

    Joined:
    26 Sep 2019
    Messages:
    6,547
    Thanks Received:
    1,724
    Location:
    North
    Country:
    United Kingdom
    Existing room thermostats use L, N and N/o, Nest will use on/off via T1 and T2. So put the wires L and N/O into these, this will then send 12v to the Nest thermostat. Remove the neutral wire at the wiring centre and safely terminate at other end. You I’ll need an earth connection doing it this way though. Do not bridge any connections here. Repeat above for heatlink number 2.
     
  8. Jessica L

    Jessica L

    Joined:
    7 May 2021
    Messages:
    5
    Thanks Received:
    2
    Country:
    United Kingdom
    UPDATE: Over the weekend I've managed to install the Nest thermostat. Initially I went with scenario #2 and removed CH1 ON, CH2 ON and HW ON from the programmer completely from both ends (wiring centre and programmer downstairs). Then with a new wire, I wired only HW ON to the Heatlink1 #6 and followed scenario #2 for the rest.

    The issue was I didn't have 240V coming from the N and L1 of the Room Stat 1 and Room Stat 2 on the wiring centre.
    With all the wires in the current state, I looked for 240V somewhere where I could power the two Heatlinks. I found it from the N and L of the programmer section that wasn't being used previously.

    I've attached a diagram of what I did.
    Black arrow was the existing wiring setup.
    IMG_8667.jpg
    Good luck to all and hope someone will find this helpful.
     
    Last edited: 10 May 2021
    • Thanks Thanks x 1
  9. Sponsored Links
Loading...

Share This Page