Heat Pump Water Heater Sizing Calculator

Water Heater Sizing Formula:

\[ \text{Size} = \frac{\text{Daily Usage}}{\text{Recovery Rate}} \]

Recommended Tank Size (hours):

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1. What is a Heat Pump Water Heater Sizing Calculator?

Definition: This calculator determines the appropriate size (in runtime hours) for a heat pump water heater based on daily hot water usage and the unit's recovery rate.

Purpose: It helps homeowners and contractors properly size heat pump water heaters for optimal performance and energy efficiency.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \text{Size} = \frac{\text{Daily Usage}}{\text{Recovery Rate}} \]

Where:

Size — Recommended runtime hours needed
Daily Usage — Total hot water consumption (gallons)
Recovery Rate — Heater's water heating capacity (gallons/hour)

Explanation: The calculation determines how many hours your heat pump water heater needs to run to meet your daily hot water demand.

3. Importance of Proper Sizing

Details: Correct sizing ensures efficient operation, prevents running out of hot water, and maximizes energy savings from the heat pump technology.

4. Using the Calculator

Tips: Enter your household's daily hot water usage in gallons and the recovery rate of your heat pump water heater (default 20 gallons/hour). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical recovery rate for heat pump water heaters?
A: Most residential units have recovery rates between 15-25 gallons per hour, depending on model and conditions.

Q2: How do I estimate my daily hot water usage?
A: Average household uses about 20 gallons per person daily. Showers (2 gpm), laundry (15-30 gal/load), and dishwashing (4-6 gal/load) are major contributors.

Q3: Why is the result in hours rather than gallons?
A: Heat pump water heaters heat water more slowly but more efficiently. The result tells you how long the unit needs to run to meet your daily demand.

Q4: Should I round up the result?
A: Yes, consider rounding up to the nearest whole hour to ensure adequate hot water supply, especially during high-demand periods.

Q5: Does this account for temperature rise?
A: Recovery rates are typically given for a standard temperature rise (usually 90°F). For greater temperature differences, the actual recovery rate may be lower.