For me useless! The cable of the supplied external temperature sensor is extremely inflexible and impossible to move into flush pipes. A broken clock thermostat and the external sensor should be replaced. Unfortunately, the cable supplied is unusually rigid and can not be in the flush pipe (with several bends) collect. The old sensor had to back in and now provides a different temperature curve. I'm still thinking if I return the whole system.
The two mapped binding wires can be saved actually. The cable ring returns to a pulling apart like a spring back into its delivery position.
