1. What is a Hot Water Recovery Time Calculator?

Definition: This calculator estimates how long it takes for a water heater to recover (heat up) a specified volume of water by a certain temperature.

Purpose: It helps homeowners, plumbers, and engineers determine water heater performance and size requirements.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Time \) — Recovery time (hours)
• \( Volume \) — Water volume (gallons)
• \( \Delta T \) — Temperature change (°F)
• \( BTU/h \) — Heater capacity (BTU per hour)
• \( 8.34 \) — Weight of 1 gallon of water (lbs)

Explanation: The formula calculates the energy needed to heat the water and divides it by the heater's output capacity.

3. Importance of Recovery Time Calculation

Details: Proper recovery time estimation ensures adequate hot water supply, proper heater sizing, and energy efficiency.

4. Using the Calculator

Tips: Enter the water volume in gallons, desired temperature increase (°F), and heater capacity (BTU/h). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is 8.34 used in the formula?
A: It represents the weight of one gallon of water in pounds, needed to convert volume to mass for heat calculations.

Q2: What's a typical ΔT for residential water heaters?
A: Most heaters raise water temperature by 70-80°F (from 50°F groundwater to 120-130°F output).

Q3: How do I find my water heater's BTU rating?
A: Check the manufacturer's label or specifications (residential units typically range 30,000-75,000 BTU/h).

Q4: Does this account for heat loss?
A: No, this calculates ideal recovery time. Actual times may be longer due to system inefficiencies.

Q5: Can I use this for tankless water heaters?
A: Yes, but tankless heaters typically provide continuous flow rather than recovery.