Cheapest processing - improper function

Saving energy is on everyone's lips. No wonder the are even declined somewhat during the economic crisis is heating energy prices still an ever-growing point of the charge settlement.
Accordingly, I have purchased the thermostat model at the hardware store. Two pieces cost here in the "value pack" 50Euro-incl. Vent valves.

It is installed without too much difficulty. Take the old thermostat from, seeking the appropriate adapter and screw the new one. Even here, however, falls the "cheap" processing. PVC nuts and adapter rings, one of the thermostats refuses to work already at power first. The PVC thread of another Themrostates held this unsure on the heating - processing technology totally unacceptable.

The programming takes place simply and is also the layman feasible. However, the desired 21Grad I had never in the room because the Themrostat seals off at 19,5Grad. This deviation, paired with said processing problems cause I'll replace my thermostat by higher quality and nice DIY retailers can find another customer. Maybe it is in my purchase yes to Monday models - recommended I can not anyway. The stars are only based on the price and the fact nevertheless a sufficient function.