Need some help with installation

[Jeppa]

Hi,

I´m struggling on how to connect my nest learning thermostat to my old central heating system.

I have a gasburner Buderus Logano G124X. It has a controller on top Logamatic R2109.

Connected to the burner is a Radson EBU boiler. 

The thermostat I want to replace is a Siemens REV1. It has 2 batteries and 2 cables running towards the controller of the burner.

I don´t know if I should connect to the ON/OFF or the OpenTherm. I think because of the age, it is only ON/OFF system. 

I suppose I should follow the 230V combi boiler scheme in the nest guide.

The heating of the tapwater is conteolled by the logamatic already.

Any thoughts on this?

Thanks,

Jeppa

 Orange block is for the thermostat connection on the Logamatic controller.

[Jhonleanmel]

Hi Jeppa,

Thanks for the photos and for posting.

Your wire label indicates an incompatible system.

These systems usually only work with thermostats made by the same manufacturer. But some incompatible systems may also have the option to use standard heating system wires. Contact a local pro and have them check if your system can be rewired to be Nest compatible.

Best,
Mel

[Jeppa]

Thanks for your reply.

I got it working! 

The contact was a potential free one (dry contact). 

With this connection scheme, it works fine.

[Jhonleanmel]

Hey there Jeppa, 

Awesome — glad to hear that your issue is fixed. It looks like we can consider this one complete, so I will lock the thread shortly unless I can help out with anything else. 

Best, 
Mel