Hi... I have an infloor heating system install (Schluter Ditra system), that needs to be run on a 240 volt breaker. I've installed a 14/2 wire from the thermostat box to the breaker, and install a 15 amp, 240 volt double pole breaker. I've connected both the black and the white (usually neutral) wires to the breaker and wrapped the white wire in black to signify that it's being used as a hot line. I've connected both wires to the thermostat, and again wrapped the white to signify its use as a hot wire.
But... the thermostat won't turn on. Any suggestions? The breaker isn't tripping, and I think there is power at the thermostat line, but it's just not running.
Thanks a lot!

I think there is power at the thermostat line
Get a meter and be sure.

Describe the wiring to the cables.

Have you checked the heating cables for continuity?

Are you sure you connected it line and load sides? Some t'stats have a 4 connector block, the 2 center screws are line, outside are load.