Enter the volume of the tank, temperature of hot and cold water, heating capacity, and efficiency of the heater into the calculator to determine the hot water recovery time.
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Hot Water Recovery Formula
The following formula is used to calculate the hot water recovery time for a given set of parameters.
R = \frac{8.34 \times V \times (T_h - T_c)}{H \times E}Variables:
- R is the hot water recovery time in hours (multiply by 60 for minutes)
- V is the volume of the tank in gallons
- T_h is the temperature of the hot water in degrees Fahrenheit
- T_c is the temperature of the cold water in degrees Fahrenheit
- H is the heating capacity of the heater in BTU/hr
- E is the efficiency of the heater as a decimal
- 8.34 is the approximate weight of 1 US gallon of water in pounds (lb/gal)
To calculate the hot water recovery time, multiply the volume of the tank by 8.34 and by the difference between the hot and cold water temperatures to get the required energy in BTU. Divide the result by the product of the heating capacity (BTU/hr) and the efficiency to get hours (then multiply by 60 to get minutes).
What is Hot Water Recovery?
Hot water recovery refers to the time it takes for a water heater to heat a full tank of water to the desired temperature after it has been depleted. This is an important factor in ensuring that there is always a sufficient supply of hot water available for use. The recovery time can be influenced by several factors, including the volume of the tank, the temperature of the incoming cold water, the desired temperature of the hot water, the heating capacity of the heater, and the efficiency of the heater. Understanding and calculating the hot water recovery time can help in selecting the right water heater for your needs and ensuring optimal performance.
How to Calculate Hot Water Recovery?
The following steps outline how to calculate the hot water recovery time.
- First, determine the volume of the tank (V).
- Next, determine the temperature of the hot water (T_h).
- Next, determine the temperature of the cold water (T_c).
- Next, determine the heating capacity of the heater (H).
- Next, determine the efficiency of the heater (E).
- Finally, calculate the hot water recovery time using the formula R = (8.34 × V × (T_h – T_c)) / (H × E). (This gives R in hours; multiply by 60 for minutes.)
- After inserting the values and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
Volume of Tank (V) = 50 gallons
Temperature of Hot Water (T_h) = 140°F
Temperature of Cold Water (T_c) = 60°F
Heating Capacity of Heater (H) = 40,000 BTU/hr
Efficiency of Heater (E) = 0.9