Firemaking

Unlocked after producing your first log.

There are two sections in Fire Making. Fire and Rewards

Fire
There are two things here, heat, which is used for cooking and smelting advanced ores, and the Demon Butler.

Here is a table of heat production.

The demon butler is simply used to collect all of the rewards below.

Rewards
When you reach certain amounts of heat you unlock rewards, these have various tiers and reward. Typical cooldown is 12 hours.

Research
Each level or research upgrades this to a better version.