Heat is the equivalent of Room Ink in the Circuits V2 world.

You can see the amount of Heat being used per-frame in the Circuits V2 tab of your Palette.

In Circuits V1 we overestimate the cost of chips by assuming they are all running constantly. In Circuits V2 we only calculate the cost of chips while they are actually running.

This means that you only see Heat costs while a graph is executing.

Branches in execution will also impact how much Heat is consumed per frame.

Executing a long branch takes more Heat than executing its smaller counterpart.

Heat is calculated per-frame. When you run out of Heat your graph stops executing for the rest of the frame.

On subsequent frames execution continues at the beginning of new events, not where it was halted.