bolier thermostat voltage

[johnmcnamee]

I have a Worcester/Bosch Greenstar boiler in the uk. This is a very popular boiler. I am installing a Nest E unit. The installation instructions say it is not suitable for 240v circuits - but this is a very popular boiler so I find it surprising that it would be incompatible, but it uses 240v circuits.

Is the following assumption correct?

The boiler expects a 240 volt signal back from the thermostat, so you connect two wires - a live feed and a live return - through the nest, but these are at 240 volts. The Nest itself is controlled by its batteries at low voltage - its job is to simply connect the two wires with its relay so the circuit it contols is a 240 volt circuit, although the controller itself is running at battery voltage.

Is that right?

John

[boblapsley1]

Hi John the two terminals in my boiler are only a switch (there is no voltage present) therefore I connected it to my nest controller. You can check these terminals when your boiler is powered up to make sure there is no high voltage present. To check this before you connect your nest, put a link between the two terminals to see if the boiler comes on.

[Jhonleanmel]

Hey folks, 

We appreciate your help here, @boblapsley1.
@johnmcnamee, I wanted to follow up and see if you are still in need of any help. Please let me know if you are still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

Thanks,
Mel

[Dan_A]

Hey there,

I'm chiming in to ensure you've got the answer you're looking for. Feel free to let us know if you have more questions about this.

Best,

Dan

[Dan_A]

Hi folks,

We haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you need assistance or want to discuss topics, feel free to start a new thread.

Thanks,

Dan