1. What is a Tankless Water Heater Flow Rate Calculator?

Definition: This calculator determines the maximum flow rate that a tankless water heater can deliver based on its heat output and the desired temperature rise.

Purpose: It helps homeowners and plumbers size tankless water heaters appropriately for their needs.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (m³/s)
• heat — Heat input from the water heater (W)
• \( \rho \) — Water density (kg/m³, default 1000)
• \( c_p \) — Specific heat of water (J/kg·K, default 4186)
• \( \Delta T \) — Temperature rise (K)

Explanation: The heat input is divided by the product of water density, specific heat, and temperature rise to determine how much water can be heated per second.

3. Importance of Flow Rate Calculation

Details: Proper flow rate calculation ensures your tankless water heater can meet your hot water demands without temperature fluctuations.

4. Using the Calculator

Tips: Enter the heater's heat output in watts, water density (default 1000 kg/m³), specific heat (default 4186 J/kg·K), and desired temperature rise in Kelvin. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical temperature rise for showering?
A: For showering, a typical ΔT is about 25-30K (from 10°C cold water to 35-40°C).

Q2: How do I convert m³/s to more practical units?
A: Multiply by 1000 for liters/second, or by 60000 for liters/minute.

Q3: Why are density and specific heat pre-filled?
A: These are standard values for water at room temperature and rarely need adjustment.

Q4: How do I find my heater's heat input?
A: Check the manufacturer's specifications, usually listed in kW (1 kW = 1000 W).

Q5: Does this account for multiple fixtures?
A: No, this calculates maximum flow for one fixture. For multiple fixtures, sum their flow rates.