1. What is a Tankless Water Heater Calculator?

Definition: This calculator determines the power (in kW) required for a tankless water heater based on flow rate and desired temperature rise.

Purpose: It helps homeowners and plumbers properly size tankless water heaters for residential or commercial applications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( kW \) — Required power (kilowatts)
• \( GPM \) — Flow rate (gallons per minute)
• \( \Delta T \) — Temperature rise (°F)
• 2.4 — Conversion factor (accounts for water's specific heat)

Explanation: The formula calculates the energy needed to heat a given water flow by a specified temperature difference.

3. Importance of Proper Sizing

Details: Correctly sizing a tankless water heater ensures adequate hot water supply without overspending on excessive capacity.

4. Using the Calculator

Tips: Enter your desired flow rate (GPM) and the temperature rise needed (difference between incoming water and desired output). Default ΔT is 70°F (typical for 50°F incoming to 120°F output).

5. Frequently Asked Questions (FAQ)

Q1: What's a typical flow rate for residential use?
A: Showers typically use 1.5-2.5 GPM, while whole-house systems may need 5-10 GPM depending on simultaneous fixtures.

Q2: Why is temperature rise important?
A: Colder incoming water requires more energy to reach desired temperature. Groundwater temperature varies by location and season.

Q3: What if my calculated kW isn't a standard size?
A: Round up to the nearest available unit size for safety margin.

Q4: Does this account for efficiency losses?
A: No, consider adding 10-20% to the calculated power if your unit isn't 100% efficient.

Q5: Can I use this for multiple fixtures?
A: Yes, sum the GPM of all fixtures that might run simultaneously for whole-house sizing.