Drayton LP241 + Digistat SCR -> Nest 3rd Gen - Help!

[m10d]

Hi,

I’m trying to install a Nest 3rd Generation to replace my current thermostat and programmer:

• Programmer: Drayton LP241 Programmer
• Thermostat: Digistat SCR

So far I’ve tried this (based on @stem's answer here: https://www.diynot.com/diy/threads/drayton-lp241-to-nest-3rd-gen-help.553839/post-4744873)

• Drayton LP241 N = Nest Heat Link N
• Drayton LP241 L = Nest Heat Link L
• Drayton LP241 3 = Nest Heat Link 6
• Drayton LP241 4 = Nest Heat Link 3
• Drayton LP241 1 = Nest Heat Link 4
  
  
• Drayton LP241 Earth = Nest Heat Link Earth
• Link between Nest Heat Link L and 2
• Link between Nest Heat Link 2 and 5
• Disconnected all thermostat wires from the wiring centre
• Link between the wiring centre terminals that the original thermostat wires 1 and 3 came from (2nd and 5th down on the left in the image)
• Plug Nest Thermostat in at the wall using the Nest Stand and connect to the Heat Link over wifi

Results:

• The heating and water come on if I press the manual button on the Heat Link.
• The water comes on if I boost it from the Nest App.
• But the heating does not come on when I set the temperature on the Nest App or on the Thermostat, even though the Heat Link has the green light showing that it is connected to the Thermostat.

Could anyone help me understand what I’m doing wrong? Thanks!

Digistat thermostat

LP241 Programmer

Wiring centre

Nest Heat Link

 

[CBW]

Are you sure you linked the previous thermostat live and switched live together?

 

[ianmcd]

Link between the wiring centre terminals that the original thermostat wires 1 and 3 came from (2nd and 5th down on the left in the image

cant see any link in your pic

 

[m10d]

The pics are just of the old setup and the instructions for the Nest Heat Link. I can post pics of what I've tried if helpful.

 

[CBW]

I can post pics of what I've tried if helpful.

Yes, it would be helpful.

 

[ianmcd]

yes post a pic of the wiring centre as it is now and a pic of the nest when ch only is selected and calling for heat

 

[m10d]

Here's the Nest Heat Link and the wiring centre as they are now. Blue wire coming out of the top of the wiring centre picture is the link.

You can see I've removed the thermostat N, L and E from the wiring centre and linked the C and NO terminals (with the long blue wire).

I just checked and the heating comes on when I turn on the hot water in the Nest App... very confused.

 

[stem]

Looking at your original photo, if the cable with the wires I've marked with a red X go to the thermostat terminals 1 and 3, and you have removed the cable from the wiring centre and replaced it with the link shown in red, then that is the correct way to decommission the thermostat.

So, your 'after' photo (assuming the two blue wires are opposite ends of the same wire connected in a loop) looks right. Was the system working properly before you installed the Nest?

 

[m10d]

Yep, those are the wires that went to terminals 1 and 3 for the termostat, and the two blue wires in the after photo are just opposite ends of the same wire.

And yeah, the system was working fine before.