After about an hour, the Bluetooth connection broke down and could not be re-enabled. Hour Long fumbling on the chest strap and iPhone brought no remedy. Wanted to return the belt already, since a tip from the network brought a solution: resettet remove transmitter battery and short-circuit using a paper clip for several seconds the transmitter device. Then reconnect. Then he ran so far without further interruptions.
The Bluetooth connection to the iPhone provides continuous heart rate data, but the 5 kHz function could be used by any of my exercise bike, while indicating that they received something to 5kHz. Ok was, for me, although the reason is not to take the Wahoo, but after data arrive at the iPhone.