1. What is a Tankless Water Heater Size Calculator?

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

Purpose: It helps homeowners and plumbers select the appropriately sized tankless water heater for their needs.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (liters per second)
• \( \Delta T \) — Temperature difference between incoming and desired water (°C)
• 3412 — Conversion factor (BTU/kWh)

Explanation: The formula calculates the energy required to heat a given flow of water by a specified temperature rise.

3. Importance of Proper Sizing

Details: Correct sizing ensures adequate hot water supply while avoiding energy waste from an oversized unit or insufficient heating from an undersized one.

4. Using the Calculator

Tips: Measure your peak flow rate (sum of all fixtures that might run simultaneously) and determine your needed temperature rise (typically 30-50°C above groundwater temperature).

5. Frequently Asked Questions (FAQ)

Q1: How do I measure flow rate?
A: Time how many liters fill a container in one second, or sum the flow rates of all fixtures that might run simultaneously.

Q2: What's a typical temperature rise?
A: Most systems are designed for a 35-45°C rise, depending on your incoming water temperature and desired output.

Q3: Why is the conversion factor 3412?
A: This converts between BTU and kWh (1 kWh = 3412 BTU), as heating calculations often use BTU but tankless heaters are rated in kW.

Q4: Should I add a safety factor?
A: It's common to add 10-20% to the calculated size to account for variations in incoming water temperature and flow rate.

Q5: Can this be used for whole-house systems?
A: Yes, but be sure to calculate for your peak simultaneous hot water demand, not just individual fixtures.