What was the core inefficiency Watt identified in the Newcomen engine?

Answer

The constant cycle of heating and cooling the main cylinder with every stroke wasted energy.

Watt realized that the process of injecting cold water directly into the cylinder to condense steam immediately destroyed the heat stored in the metal walls, causing the machine to waste nearly 75 percent of the supplied coal energy on reheating the cylinder.

What was the core inefficiency Watt identified in the Newcomen engine?
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