1. What is a Cast Iron Radiator BTU Output Calculator?

Definition: This calculator estimates the heat output (in BTUs) of cast iron radiators based on temperature difference, heat transfer coefficient, and surface area.

Purpose: It helps HVAC professionals and homeowners determine the heating capacity of cast iron radiators for proper system sizing.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Heat output (BTU/h)
• \( \Delta T \) — Temperature difference between radiator and room (°F)
• \( K \) — Heat transfer coefficient (BTU/h·ft²·°F)
• \( A \) — Radiator surface area (ft²)

Explanation: The temperature difference drives heat transfer, multiplied by the radiator's efficiency (K) and its size (A) to determine total heat output.

3. Importance of BTU Calculation

Details: Accurate BTU output estimation ensures proper heating system design, energy efficiency, and comfortable indoor temperatures.

4. Using the Calculator

Tips: Enter the temperature difference (typically 100-150°F), heat transfer coefficient (default 2.5 for cast iron), and radiator surface area. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical ΔT for cast iron radiators?
A: Most systems operate with a ΔT of 100-150°F between radiator surface and room temperature.

Q2: What's the standard K value for cast iron?
A: Cast iron typically has a K value of 2.5 BTU/h·ft²·°F, but this can vary with radiator design.

Q3: How do I measure radiator surface area?
A: Calculate the total exposed surface area including all fins and sections, or consult manufacturer specifications.

Q4: Does this account for steam vs. hot water systems?
A: The ΔT should reflect your actual operating conditions - steam radiators typically have higher ΔT than hot water.

Q5: How accurate is this calculation?
A: It provides a good estimate, but actual output may vary due to factors like airflow, paint condition, and installation.