Shardlight

Give him the chalk from when you scared him off in the market (by making him draw tiberius and hitting the bell with the xbow)

Look at AND interact with: valve, furnace, drain, hanging artwork, drawings near Denby, sketch of you (look at it twice!), burnt drawings, glass horse
turn on the gas and try to leave the factory
look at (AND interact with) the opening of the furnace while the gas is on
turn on the gas off again
use any item (apart from wood, bucket or salt) with the opening of the furnace
use the wood plank [inventory] with the unlit furnace opening
use the salt [Inventory] with the furnace opening
use the gun [Inventory] with the furnace opening
turn the gas on by using the valve
use the gun [Inventory] with the opening of the furnace to light the fire
look at the lit furnace opening
interact with the lit furnace opening
use the wood plank [Inventory] on the lit furnace opening
turn the gas off
put wood [Inventory] in your bucket [Inventory]
use the bucket with wood [Inventory] with the opening of the furnace
turn the gas on by using the valve
use the gun [Inventory] with the opening of the furnace to light the fire
turn the gas off again
take the bucket from the opening
go outside and take another piece of wood
go back input wood [Inventory] in your bucket [Inventory]
put salt [Inventory] in your bucket [Inventory]
put the bucket [Inventory] in the furnace
turn the gas on by using the valve
use the gun [Inventory] with the opening of the furnace to light the fire
turn the gas off again
get the stuff from the furnace

I just wanted to add that you can do this in your sole playthrough, just make sure to turn it on before starting the game and you can get all the other achievos too.