To calculate the total time it takes to heat a pool:
\[ T = \frac{S \times 8.33 \times t}{HP} \]
To calculate a pool heat time, multiply the size of the pool in gallons by 8.33 times the desired temperature, then divide by the heater output power.
Let's assume the following values:
Step 1: Multiply the size of the pool by 8.33 and the desired temperature rise:
\[ S \times 8.33 \times t = 10,000 \times 8.33 \times 20 = 1,666,000 \]
Step 2: Divide by the heater output power:
\[ T = \frac{1,666,000}{100,000} = 16.66 \text{ hours} \]