Comment by zabzonk

Personally, I keep things simple. Got a new (pretty basic) Honeywell thermostat after a kitchen fire; thermostat was pretty old anyway. For wiring, you mostly have 2-wire and 3-wire although there are a lot of variations as you get fancier: https://nassaunationalcable.com/blogs/blog/a-full-guide-to-t...

Number of zones in the house may affect things as may boiler only or AC being in the picture as well.

Thermostats (aka space temperature sensors) can have between two and eight wires. A boiler will usually have three: 24V power, call for heat, and common.

If your boiler has inputs on the terminal block for a thermostat, I would highly recommend buying a wired one, the 24V constant power removes the need for batteries.

If you can provide a link to your boiler’s installation and operations manual, I can tell you.

> good link on how the thermostat gets paired with the boiler?

You should have a book with the boiler that says how your system is setup. They nearly always include schematics and are very helpful. Typically you can open a cover and see the wiring details as well.

Forget about web sites, there are too many different ways a system can be setup, so even if they are not slop they can still be inapplicable for you. Once you know what you are looking at you can sometimes get useful information from the web, but until then you can't sort out what is useful for you.