Hi,
I am attaching some references from MathWorks website that describe how to model a heater in Simulink. The references are:
- Thermal Model of a House - MATLAB & Simulink (mathworks.com)
- Model A House Heating System - MATLAB & Simulink (mathworks.com)
- Modeling Heat Transfer of a Projector - Video - MATLAB & Simulink (mathworks.com)
- Vehicle HVAC System - MATLAB & Simulink (mathworks.com)
Hope this helps.