Steampunk: How far could have steam tech gone in the past?

[Mr. Oragahn]

Putting aside the debate about how unefficient steam is when it comes to energy, I'm wonderng how far european societies of the 19th century push steam based technologies based on what already existed, but pushed to extremes, and how could they keep the necessary levels of pressure with the materials and sealing techniques they had at their disposal?

What would be the raw material consumption to lit the fires necessary to raising water temperature (if water is used in this case) for example?

Would steamplants be built and sent at high altitudes, or deep down water levels, or underground?

You can even think of furnaces hundreds of meters wide if you want.

I just wish to know how far steamtech could have been pushed back then, with a bit of out-of-the-box thinking.