Why is my floor not heating but there are no error messages?
MSTAT Manual Thermostat
If your floor is not heating, and there is no error message this could be due to a programming issue.
Go back through the programming and check that the temperature when the heating is set to be on is high enough. Make sure that your target temperature is higher than the floor temperature reading, between 23²C -28°C is a comfortable floor temperature.
You should also consider what your subfloor type is. If your system has been installed on a concrete slab or over an unheated space and no insulation was used, downward heat loss will cause your heating system to warm your floor much more slowly.
Lastly, if you find that you have the correct temperature settings and the floor has been insulated there may be a fault with the underfloor heating system.
An electrician will need to conduct a resistance test on the heaters to ensure that there is a circuit under the floor.