Thermal load is demand for heat energy. The heat may be needed for space heating, hot water heating, or some industrial process. The thermal load can be served by the boiler, by a generator from which waste heat can be recovered, or by surplus electricity. If you want a generator to serve the thermal load with waste heat, you must specify a non-zero value for that generator's heat recovery ratio. If you want surplus electricity to serve the thermal load, you must add a thermal load controller.
Click either the Thermal #1 or Thermal #2 button to open the Thermal Load Set Up page. The details of a load in a given system are sometimes not available, so HOMER can build (simulate) a load in several ways (see Adding a Load). After HOMER creates the load, you can edit it in several ways, including modifying individual time steps.
After you have added a load, you can make changes on the Thermal Load page. See the Load Profile section of the help.