Power Nest with Plug-In Transformer

[4head]

I have a two-wire battery operated thermostat and want to replace it with a 3rd Generation Nest Learning Thermostat to heat up my house using a boiler.

I have come across three methods to achieve this on the internet using a plug-in 24V transformer and want to know which is the correct and best way:

Method 1: 

Nest Rh to R on Boiler

Nest W1 to W on Boiler

Nest Rc to 24v Plug-in Transformer

Nest C to 24v Plug-in Transformer

Method 2:

Nest Rh to 24v Plug-in Transformer

Nest C to 24v Plug-in Transformer

Nest W1 to W on Boiler

No Contact to R on Boiler

Method 3:

Nest Rh to 24v Plug-In Thermometer

Nest Rh to R on Boiler

Nest W1 to W on Boiler

Nest C to 24v Plug-in Thermometer

[DeboraJ]

Hi @4head,

Thanks for reaching out to the community! I understand that you’re looking for the best wiring recommendation to replace your two-wire battery thermostat with a Nest Learning Thermostat 3rd Generation. Let me help you find the best option!

Before we move forward, I need some information to provide you with the most accurate steps:

• Could you please share with us a photo of the current wiring that you have?
• What type of HVAC system do you have?
• Could you share with us a photo of the current thermostat that you have installed?
• You can upload the photos directly here or share a Google Drive link (please ensure the link permissions are set to 'Anyone with the link').

Once you provide this information, I will be more than happy to assist you!

Best regards,

Debora