Can the boiler work out whether it is connected to a controller over the EMS bus automatically, so there doesn't need to be a separate configuration step?

Could you have HA controlling a relay that can operate the boiler in on/off mode so normally it's just on so it will use the EMS link but if the EMS link does stop working you can still control it that way as a backup?

We have a Tado; I always intended to add a Shelly between Tado and boiler so I could override it if the Tado stopped working for any reason, but never quite got round to it...

 

Can the Tado be fixed? If so, it has excellent integration with Home Assistant so everything can be run locally.

 

Well, I don't know. But there's pretty much nothing anyone can do to convince me that having your heating totally dependent on the internet and someone else's server working is a sane idea. And some searching of the Tado forums turns up far too many people saying things like "I've been without heating for a week so far in the middle of winter and Tado won't reply to my emails".

When we moved into this house, the heating was all set up with Tado, but (since we had just moved in) we were without internet for a week, which meant that we couldn't turn the heating on. Once our internet was installed, I tried to get the Tado system working, but just couldn't get it to work properly: the app would say that the heating is running because the set point is 19° and the room temperature is 15°, which seems fine, except the boiler wasn't running and the thermostat itself said "off". Despite lots of button pushing, I could not get the thermostat do do anything other than say "off". Eventually I decided to factory reset the thermostat and re-pair it, except it won't pair with the gateway. There is no kind of log that might tell you why it won't pair, it just says nope.

So my experience with the Tado system has done nothing but re-enforce my initial belief that the whole idea is nonsense and I would prefer to run something that I am in control of and stand some chance of debugging if it goes wrong.

 

I’m curious on what you intend to do in terms of control logic that make the change between relay control or bus control any “better”? Other than perhaps avoiding the need for some external (to the boiler) temperature sensors to read flow and return temps, then even with on-off control the boiler still modulates based on the measured differential betwenn its own flow & return sensors.

 

Other than perhaps avoiding the need for some external (to the boiler) temperature sensors to read flow and return temps, then even with on-off control the boiler still modulates based on the measured differential betwenn its own flow & return sensors.

We have a WB Greenstar i30-something boiler as well; I vaguely remember reading its minimum power was something ridiculous like 9kw anyway, so even if it can modulate down when using EMS I always wondered if it can actually modulate down far enough to actually make any difference.

You could change the flow temperature manually but ours really didn't like setting it below about 40 degrees, it would just decide to pump round room temperature water for ages without actually turning the burner on.