1. What is an Electric Tankless Hot Water Heater Calculator?

Definition: This calculator determines the required size of an electric tankless water heater based on your simultaneous hot water needs.

Purpose: It helps homeowners and plumbers properly size tankless water heaters to ensure adequate hot water supply.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Total flow rate (gallons per minute)
• \( Q_i \) — Flow rate of each fixture

Explanation: The calculator sums the flow rates of all fixtures that might run simultaneously to determine peak demand.

3. Importance of Proper Sizing

Details: Undersized heaters can't meet demand, while oversized units waste energy and cost more. Proper sizing ensures efficient operation.

4. Using the Calculator

Tips: Count all fixtures that might run simultaneously. Typical flow rates:

• Shower: 2.5 GPM
• Sink: 1.5 GPM
• Dishwasher: 1.5 GPM
• Washing Machine: 2.0 GPM

5. Frequently Asked Questions (FAQ)

Q1: What's the typical GPM needed for a home?
A: Most homes need 5-10 GPM. 2-3 GPM for apartments, 7-10 GPM for larger homes.

Q2: How does temperature rise affect sizing?
A: Higher temperature rises require more power. This calculator assumes standard 70°F rise.

Q3: Can I run multiple fixtures simultaneously?
A: Yes, but total GPM must not exceed heater capacity. This calculator helps determine that.

Q4: What electrical service is needed?
A: 36 kW needs 150A, 54 kW needs 225A, 72 kW needs 300A service minimum.

Q5: Should I round up my GPM calculation?
A: Yes, add 10-20% buffer for safety and future needs.