If OP ever shows up here, you probably could have just replaced the thermostat with one that is compatible with your boiler for less money and headache. The boiler market is fairly open to competition as evidenced by the fact that you could find a Honeywell signal in a random OSS project that also worked.
Good luck with your future apartment customizations!
Depends where you are. Where I live it's no modification. If it's hard-wired the tenant can't touch it.
Though in reality many landlords don't mind as long as you know what you're doing and return it to how it was. Just a problem if you get a jerk landlord.
Here a landlord can do an inspection with 48 hours notice. If you're out of town they are allowed access without you present. Also the landlord can end your tenancy with 90 days notice with no reason.
Penalties would depend on the adjudicator's opinion of the damages and risk.
Agreed (I set up our dual zone Nest-controllee heating so I know it's not difficult), but what happens if the landlord visits and isn't happy with you having done this? It would be a pain to have to revert this if you knew the landlord was coming.
Depends on jurisdiction, of course, but often you’re allowed to modify things as long as you return it to how it was before when you leave. Obviously not quite as simple as that always but I would guess in many placing temporarily replacing a simple thermostat would fall under that.
You just take the thermostat off the wall and put it in a drawer and then you buy a new thermostat and put it on the wall and then when you give the apartment back, you take the old thermostat and you put it back on the wall
Also, if you read this far, are you German or something? you can just do things. which OP seems to know. And even if the landlord came and saw the apartment as long as the new thermostat isn’t neon orange, he isn’t going to notice and even if he somehow noticed you would just gaslight him and say no that’s how it’s always been and how the hell is he gonna escalate past that? And why would he if the new thermostat is more expensive and has better features?
Good luck with your future apartment customizations!