A condensate pump is located 75 feet below the feed water heater, and its discharged gauge reads 75 PSI. The pressure at the inlet to the heater is _______ psi.

To determine the pressure at the inlet to the heater, it's important to consider the relationship between pressure, elevation, and the specifics of the system involved.

The condensate pump's discharge gauge reads 75 PSI. However, because the pump is located 75 feet below the feed water heater, you need to account for the hydrostatic pressure due to the height difference when calculating the pressure at the inlet to the heater.

The hydrostatic pressure can be calculated using the formula:

[ \text{Hydrostatic Pressure (PSI)} = \frac{\text{Height (feet)} \times \text{Specific Weight of Water (lbs/ft³)}}{144} ]

The specific weight of water is approximately 62.4 lbs/ft³. Therefore, the hydrostatic pressure from the 75-foot height is:

[ 75 , \text{ft} \times \frac{62.4 , \text{lbs/ft³}}{144} \approx 32.56 , \text{PSI} ]

Subtracting this hydrostatic pressure from the discharge gauge pressure gives:

[ 75 , \text{PSI} - 32.56 , \text{PS