Tankless Water Heaters Gas Calculator

BTU Formula:

\[ BTU = \frac{Q \times 8.34 \times \Delta T \times 60}{efficiency} \]

BTU Required (BTU/h):

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1. What is a Tankless Water Heater BTU Calculator?

Definition: This calculator estimates the BTU (British Thermal Units per hour) required for a tankless water heater based on flow rate, temperature rise, and system efficiency.

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:

\[ BTU = \frac{Q \times 8.34 \times \Delta T \times 60}{efficiency} \]

Where:

\( BTU \) — British Thermal Units per hour required
\( Q \) — Flow rate in gallons per minute (gpm)
\( \Delta T \) — Temperature rise in degrees Fahrenheit (°F)
\( efficiency \) — Unit efficiency (typically 0.82 for gas tankless)
8.34 — Weight of one gallon of water in pounds
60 — Conversion from minutes to hours

Explanation: The formula calculates the energy needed to heat water at a specific flow rate through a specified temperature increase, adjusted for system efficiency.

3. Importance of Proper BTU Calculation

Details: Correct BTU sizing ensures adequate hot water supply while avoiding oversized units that waste energy or undersized units that can't meet demand.

4. Using the Calculator

Tips:

Measure your actual flow rate (gpm) from fixtures
Determine required temperature rise (incoming water temp to desired output temp)
Typical efficiency for gas tankless units is 0.82 (82%)

5. Frequently Asked Questions (FAQ)

Q1: What's a typical temperature rise for showers?
A: For 105°F shower water with 50°F incoming water, ΔT would be 55°F.

Q2: How do I measure flow rate?
A: Time how long it takes to fill a 1-gallon container at your faucet (60 seconds = 1 gpm).

Q3: Why is efficiency important?
A: Higher efficiency units require fewer BTUs to produce the same amount of hot water, saving energy.

Q4: What if I need multiple fixtures simultaneously?
A: Add the flow rates of all fixtures that might run concurrently for whole-house sizing.

Q5: What's the typical BTU range for residential units?
A: Most residential units range from 140,000 to 199,000 BTU/h, while commercial units can go higher.