This references a couple of OpenTherm project, so let's add the usual disclaimer:
The OpenTherm protocol is not open.
You can only find the spec for v2, they are now drafting v5. Yearly membership is about 3K if I remember correctly (without testing software, just for the spec).
There seems to be big difference in what you can do after v2, and it includes power delivery, maybe more fine grained control on heating curves and such (unclear, I don't have the spec)
Not all boilers support opentherm (but most should), and those who do don't support all features (but the most basic should always be present).
Thanks for the context! I didn't research OpenTherm much, since my boiler is one of the most basic models on the market. It supports just the bare minimum from V2 spec, but it works, so I'm not complaining :) This boiler was already installed when we bought the house, so not needing to replace it was a great way to save some money for remodelling.
Otherwise, I completely agree that charging 3K for the spec is a stupid money grab. When the time comes to build a new house and choose a new boiler, my choice will be influenced by what protocols are available and whether I can control the boiler with my own thermostat.
This references a couple of OpenTherm project, so let's add the usual disclaimer:
The OpenTherm protocol is not open.
You can only find the spec for v2, they are now drafting v5. Yearly membership is about 3K if I remember correctly (without testing software, just for the spec).
There seems to be big difference in what you can do after v2, and it includes power delivery, maybe more fine grained control on heating curves and such (unclear, I don't have the spec)
Not all boilers support opentherm (but most should), and those who do don't support all features (but the most basic should always be present).