Make Additional Thermostat Attributes Available in HomeKit

I have been trying to create some automation rules in HomeKit to prevent a dual fuel radiator being turned on when the central heating is on. The idea is to use the "Heating" state to turn the radiator off if turned on. I believe this state is exposed on the Air Con controller from Netatmo, but is missing from the Smart Thermostat. 

I assume there must be an attribute for this state though, as the app shows an orange background when the thermostat creates a demand and a white background when there is no demand.