I have bought a total of 3 of these thermostats in December / Januaur. Now, after only 3 months are already 2 with the error E3 (engine can not be moved) failed. Madness, what a failure rate! The manufacturer should urgently improve its quality control or not can be produced so cheaply. Even from my HR20-Style is now ( Thanks to Amazon for good and free unwinding with reimbursement. In their place, I would consider myself the manufacturer harmless, since apparently many customers have similar problems.
Addendum: So, now, the last thermostat has failed with error E3.
Conclusion: After less than a year all thermostats are faulty, default rate 100% !!! Madness ...