# Sources
Editor: Setup › Sources · Python: td.HeatSource
A heat source makes heat inside structures, at a volumetric Rate in W/µm³. A negative rate removes heat. A Heat project can also run without a source, for example with two boundaries at different temperatures.
# Add a Heat Source
Edit HeatSource form
- In Setup › Sources, click +, then Heat Source. The editor names it, for example heatsource_0.
- Set Rate and pick one or more Structures. Both are required.
sources: List of heat sources injecting energy into the simulation.
Options:
UniformHeatSource is the older, deprecated name of the same source. The editor does not offer it; see UniformHeatSource (Python client only).
# How to Choose
| If the heat … | Use … |
|---|---|
| Is made inside a structure, at a known power | A Heat Source with Rate = power / volume of the structure |
| Enters or leaves through a surface | A HeatFluxBC (see Boundary Conditions) |
# Common Mistakes
- A rate in W/m³. The editor uses W/µm³: 1 W/m³ is 1e-18 W/µm³.
- A source on a structure that you then rename or delete. The check then fails. See Heat Troubleshooting.