Factorio Forums

I have seen many stone furnace builds that try to be "up-gradable" to electric furnaces, but they all require a significant amount of rejigging of inserter arms/power poles that makes it debatable if its worth it or if a rebuild is faster. Here is my design for an up-gradable furnace setup, one that I continue to use even with blueprints (with the electric furnaces in there of course).
To Upgrade:
Replace the furnaces with electric ones.
Remove the coal/ore merger down the bottom of the build that puts ore on one side and coal on the other, and feed in 4 lines of ore to the balancer.

There is one issue with the coal & ore merger: it does not give 100% throughput, there are "hickups" because of the priority given to one side of the track over the other. This is an issue with the merger and not the furnace setup and only affects early game.

I use the following, which requires no 'adjustments' what so ever, you just remove the newly obsolete burner inserters to make room (and the fuel line can go too unless it's feeding something at the other end). Edit: I suppose you also need to get rid of the Small power poles, but I do that way sooner...as soon as I hit Energy distribution mark 1 and have the superior Medium poles (which can go on the outside and still power the inserters that need it).