For this application you can create a virtual device with the Virtual Devices app.
Create a new device with the device class Heating e.g. and the properties On/Off.
Then go into the advanced settings of this new device and fill the energy properties like this:
Energy consumption when off → 0
Energy consumption when on → 3750
Then create two flows:
When…
– Heating = On Then…
– Turn on “new device”
When…
– Heating = Off Then…
– Turn off “new device”
It’s also possible with one flow, but you must ensure that the new device is turned on when the heater is turned on, and vice versa.
When…
– Heating = On Then…
– Turn on or off “new device”