Nest 3rd Generation

[PudseyBear]

Hi

ive installed the Nest 3rd generation thermostat, heating works but not the hot water.

Switching the hot water on & off makes no change the the relay, terminal 5&6 and closed when they should be open until the hot water is switched on.

I  have it that there is a 3 core cable going upto the hot water stat and believe the wiring maybe the issue.

Red is permanent live

blue is neutral 

yellow is switch live

I currently have the yellow connected to terminal 6 on the heat link, I’m thinking that should be the red so when we switch hot water on, 230v is switched onto the red cable, the switch line I’m unsure where this would connect though?

down power the heat link and terminal 5&6 open, 4&5 close, but with nothing connected to 4,5 or 6 on power up the relay energises and remains energised.

appreciate any advice 

thanks

[Frustratedddd]

Sounds a bit worrying just having a guess!!

Upload a picture of the Heat Link connections for us to see, that makes life easy then

The picture tells you everything you should need to connect.

[PudseyBear]

I think it’s the bacteria mode, disabled that and the relay switched back.

boiler is currently not running and hot water is scheduled to come on at 5pm so we’ll see if it works

[Frustratedddd]

Bacteria will make no difference to the H/W switching on if disabled. You will see a yellow icon if the bacteria is enabled  and activated on the display.

[PudseyBear]

It was enabled, as soon as the heat link powered up the hot water relay energised (I think there was an amber led but can’t be 100%)

Disabled the bacteria mode and the relay changed back, think the tank is full of hot water now though as it hasn’t kicked back in, gone from can’t stop the hot water to waiting for it to come back on