1. What is a Radiator BTU Calculator?

Definition: This calculator estimates the heat output required from radiators based on temperature difference, heat transfer coefficient, and surface area.

Purpose: It helps homeowners and heating professionals determine the appropriate radiator size for rooms according to UK standards.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Heat output (Watts or BTU/h)
• \( \Delta T \) — Temperature difference between radiator and room (°C)
• \( K \) — Heat transfer coefficient (W/m²·K)
• \( A \) — Radiator surface area (m²)

Explanation: The temperature difference multiplied by the heat transfer coefficient and surface area gives the heat output in Watts, which is then converted to BTU/h.

3. Importance of Accurate BTU Calculation

Details: Proper heat output estimation ensures comfortable room temperatures, energy efficiency, and correct radiator sizing.

4. Using the Calculator

Tips: Enter the temperature difference (typically 50°C for UK systems), heat transfer coefficient (default 11 W/m²·K for standard radiators), and surface area. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical ΔT value for UK systems?
A: Most UK heating systems use ΔT 50°C (flow 75°C, return 65°C, room 20°C).

Q2: How does K value vary between radiators?
A: Standard panel radiators are ~11 W/m²·K, while double panel convectors may be ~13 W/m²·K.

Q3: Why calculate in both Watts and BTU?
A: Watts are standard in heating calculations, but BTU is commonly used in radiator specifications.

Q4: How do I find radiator surface area?
A: Check manufacturer specifications or measure length × height (excluding brackets).

Q5: Should I add any safety margin?
A: Consider adding 10-15% to account for heat loss through windows and external walls.