My Heizunbgsanlage had previously manual thermostatic valves "Oventrop". These connectors are not compatible with the above thermostat set. This will be indicated in the product description is missing at both Amazon and in Pearl. Only when you applied for the return at Pearl and then gets the hint, first the FAQ to read articles, you will find at the 1st digit remark that does not fit the thermostat to Oventrop valves. Therefore, only one star - not for the product, but for providers and the incomplete description.
