I am so glad I bought (most of my) EveHome setup at the business where I also bought the boiler, and with whom I have a service contract on the boiler.
My boiler is a 2006 Remeha Quinta 28c boiler, not that old. Is has been properly maintained every year since I have had it installed and it never gave me any problems with the original Celcia 20 thermostat that came with it. My experiments with a self-developed HomeSeer plugin controlling the Celcia 20 through the Remeha Gateway did unfortunately confuse the Celcia a couple of years ago: Even with the gateway removed, it regularly spontaneously jumped to 35 degrees. So I tossed the Celcia 20, replaced it with an iSense and that again has worked well for the past couple of years.
However, with the EvoHome OpenTherm boiler controller installed, the boiler regularly reports errors. In this error mode, the mode display and the temperature display on the boiler blink alternately and no heat or warm water are available. The numbers shown don't seem to be error codes, but merely the last mode and temperature from before the error occurred. All I can find on the internet is somebody writing this is a firmware error on a forum. Power-cycling the boiler doesn't cure the problem. Pressing the reset button does, but not permanently: It may come back the next day, or a couple of days later, but it will come back. Coming home in a cold house is not pleasant, especially not after having invested €1200 in a thermostat.
My boiler supplier has sent and engineer, who called Remeha and according to Remeha the burner controller in my boiler may have compatibility problems. Later burner controllers for this boiler don't have those. I consider that a defect: It's not doing something it is supposed to do.
Later my boiler supplier called Remeha again, and then they said there's only one version of burner controller for my boiler. More recent boilers have a different burner controller, but don't fit my boiler. The newer burner controllers have a feature called Smart Power, allowing to power more demanding thermostats and that should be able to deal with my OpenTherm boiler controller. He also called Honeywell for the whole past week, but they don't answer the phone (!) and don't call back on voicemail messages.
I find that a bit hard to believe: I don't think the EvoHome OpenTherm boiler controller draws that much power: Radiator valve controllers have much the same hardware, plug a motor, and they last 2 years on a battery. Plus: Smart Power is an OpenTherm 3.0 feature. If OpenTherm 3.0 is required, I thing Honeywell should have put that requirement on the box.
Now the supplier has proposed to use an EveHome on/off boiler controller on my setup, but I think that's a huge downgrade, both in performance and in efficiency, so we're in a bit of a stand off here.
Does anybody know more about OpenTherm compatibility problems with the EvoHome system? I have a fully equipped electronics workshop and I'm pretty sure I can measure power drops and/or power de boiler controller externally, but I doubt if that will help. Does anybody know more about OpenThem power supplies?