Originally Posted by
Nuclrchiller
"Delta", as used here, simply means "difference", or "differential". So, "delta T" is simply the temperature difference. In this case, the temperature difference of a medium (water or air, for example) as it flows thru a heat exchanger. As you can see, delta T is measured rather than calculated. As far as what it should be, that is best learned by finding the design specifications of the system. Each component in a system was selected to perform a specific function, under specific conditions - or range of conditions. To best determine if those components are operating correctly you need to know the design conditions, then operate the system at those conditions, and measure all parameters while operating at those design conditions. Then compare the measurements with the design specifications.