Nest Thermostat Learning and heating system

[Simi9]

Hello, Please can anyone help with Nest Learning Thermostat setting.

We have recently moved in our new house and we have a hanging gas boiler in the kitchen (Potterton) and two blue cylinders in the loft (Telford hot water cooper cylinder - indirect grade 3 and another replacement cylinder) and a black water tank on a height.

Earlier setting was being controlled by British Gas UP2. Our radiator heating was set up with the gas boiler and hot water was set up to use electricity.

We are struggling to find a way to configure nest thermostat as it is turning the gas boiler on for both heating and water.

 

[CBW]

Sounds like a faulty motorised valve rather than the nest. Do you have a 3 port valve? - likely to be in the loft or wherever the pump is located.

 

[Simi9]

Does this pic tell you anything? Everything was working as intended for the past few months so I don't think it's port valve fault but something related to nest settings.

 

[CBW]

Does this pic tell you anything? Everything was working as intended for the past few months so I don't think it's port valve fault and something related to nest settings.

Yes, appears to be a 2 port valve. Other thing to check, I believe the Nest has a legionella setting - try to access that

 

[Simi9]

Thank you for the suggestion. Bacteria setting is disabled. As soon as I put hot water on, my gas boiler starts. I want the nest to use electricity to heat water and gas boiler to central heat the house. I don't know how can I tell it to use different functions for heating and hot water.

Below is the picture of wiring of UP2 (black) and the nest heat link wiring I have done. Hope these are done correctly and is not the reason of the issue I'm facing.

 

[ianmcd]

you can only use the nest to control your immersion heaters if you install an auxillary relay.