The YT/YouTube Furnace is a furnace which arrived with the Christmas update. It is obtained through the means of redeeming a code; said code being 'sorryimlate'. It does x7 to ores upgraded by the YT Upgrader, and x3.5 to ores which weren't.
This is one of two YouTube themed items, and they both depend on each other.
The Mechanical Furnace is a furnace that you can buy in the shop. It costs $240B and multiplies ores by 6x.
If you have Tunium but can't afford this, you can use a Traveller's Tomb instead.