Install of Nest to replace Drayton LP722

[MattT]

Hi,

My parents have just bought a NEST (3rd gen) and want to replace their existing LP722.

It is a Y plan system with a Drayton Mid Position motorised Valve.

Can you advise the mapping of these from the LP722 configuration to the NEST connections.

Thank you!

 

[CBW]

Are they planning on powering the Nest thermostat with a usb or from the heatlink?

 

[MattT]

From USB

 

[CBW]

Ok, so going from the Drayton to Nest heatlink:

L to L (You also need to place link wires in the heatlink from L to 2 and 2 to 5 for common supply)
N to N
1 (Hot water off) to number 4
3 (Hot water on) to number 6
4 (heating on) to number 3
Park the earths in the earth terminal

 

[MattT]

Brilliant, thank you

 

[stem]

If there's an existing room thermostat, that should be either left set to maximum to prevent it interfering with the Nest. Or if you want to take it out, a wiring modification will be required to complete the circuit that will be left 'open' by its removal.

 

[MattT]

Oh yes that's a good point, there is no existing thermostat