Great work you did on the Nest Thermostat.
Willem van der Velden

This is brilliant! Thank you Willem van der Velden for the info, this is the first time I have heard about this. The concept looks way easier too, as the Heat Link has a relay that could control the heater, and comes with power for the EU Nest, which looks like it uses 12V DC (instead of 24V AC in the USA).

2 and 3 above would hook up to the millivolt heater, and when that circuit closes, it turns the heater on!

So it has all the functionality of the R8845U cheat-box, but with the added flexibility of being able to remote power the Nest from any outlet, instead of running wires from the Heat Link to the Nest. And it also looks way smaller!

The only thing I worry about is that it wants 230V AC power on 50 Hz for an input. It’s probably $10 on Amazon for a 110V AC to 220V AC converter that I could plug into my wall, but I wonder what the frequency difference (we have 60 Hz in the USA) would do to the 12V DC output.

My guess is that the power supply in the Heat Link could handle it, but there would only be one way to find out…