Henry you are hard-core!
Chris Vale

Here’s a pic of the relay

One I had a thought that it’s possible that the Nest could drive the millivolt circuit by itself without any help, by hooking it up like this; just maybe the solid state relay on the Nest could switch the bare millivolt signal:

But I didn’t want to try that as it was not supported by Nest, whereas the thermostat is designed to drive a 24VAC relay…

One clap, two clap, three clap, forty?

By clapping more or less, you can signal to us which stories really stand out.