The first thing you’ll want to craft is some heat conduits. These are crafted by surrounding an iron ingot with 8 wool in the crafting table like this:
These bad boys are used for moving heat from your heat producers into your heat consumers.
After making a batch of conduits you’ll want to make your first heat producer.
There is currently only one heat producer, namely the fuel burner. It’s crafted with 8 conduits around a normal furnace like this:
Now go ahead and place it down. It’ll look something like this:
Right click on the fuel burner and it’s interface will open up.
As you can see it has four slots for fuel. This is so you won’t have to bother with refueling all the time. A piece of fuel generates heat equal to the amount of items it can melt times 200. A piece of coal for example produces 1600 heat. The little bar on the right hand side is the fuel burners internal heat buffer. Once this has been filled up the fuel burner wont consume any more fuel. Heat is produced at a rate of 1 heat per tick e.g. 20 heat per second.
After getting a fuel burner you’ll probably want something to use your heat. The only heat consumer currently implemented is the insulated furnace. It’s crafted by surrounding a normal furnace with 8 pieces of wool like this:
Once you’ve placed down your insulated furnace you’ll want to connect it to you heat producer with conduits. Conduits can connect to any side of the blocks, so one way to run them is underground like this:
The internal heat buffer of the fuel burner will now begin flowing into the insulated furnace.
When you right click the furnace you’ll be greeted with it’s interface.
The insulation on the furnace allows it to run more efficiently. It has slots for three stacks of smeltables that’ll be smelted simultaneously. It takes 400 heat to complete one smelting cycle, which means you can smelt three stacks of item for two stacks worth of fuel (in a vanilla furnace). The furnace uses two heat per tick so to run it at full speed you’ll need two fuel burners running.
Both the machines have smart handling of item input/output with hoppers, Buildcraft pipes and other similar systems. The fuel burner accept items from all sides, but will only accept fuel. The insulated furnace can likewise be input to from all sides and will only accept items that can be smelted. You can also pull the output items out from any sides.