A stack temperature of 250°F above steam temperature indicates what?

A stack temperature that is significantly higher than the steam temperature, such as 250°F above, suggests inefficiency in the system. When the exhaust gases are excessively hot, it indicates that a considerable amount of heat is being lost rather than utilized effectively for heating or creating steam.

In well-functioning systems, the stack temperature should ideally be similar to the steam temperature; a large disparity signifies that energy is not being converted efficiently. The increased stack temperature can also lead to higher fuel consumption, further impacting operational costs and efficiency.

Thus, a stack temperature far exceeding the steam temperature deviates from the indicators of normal operation or good efficiency, reinforcing the notion of poor efficiency in the system.