🔥 Heater Load Calculator (ASHRAE Method)
This HVAC Heater Load Calculator helps engineers, consultants, and students calculate the required heating capacity for a room or space during winter conditions.
The calculation is based on steady-state heat loss principles recommended by ASHRAE and considers:
- Heat loss through walls, roof, and glazing
- Heat loss due to air infiltration (ACH)
- Indoor and outdoor design temperatures
- Safety margin for real-world conditions
📐 Heater Load Calculation Formula
1. Fabric Heat Loss
Q = U × A × ΔT
Where:
U = Overall heat transfer coefficient (W/m²·K)
A = Surface area (m²)
ΔT = Indoor – Outdoor temperature (°C)
2. Air Infiltration Heat Loss
Q = 0.33 × ACH × V × ΔT
ACH = Air changes per hour
V = Room volume (m³)
📊 Typical U-Values (Quick Reference)
| Construction | U-Value (W/m²·K) |
|---|---|
| Brick Wall (Uninsulated) | 1.5 – 2.0 |
| RCC Roof | 1.0 – 1.5 |
| Single Glass | 5.5 |
| Double Glass | 2.7 |
🧮 HVAC Heater Load Calculator
✅ Output Explanation
- Fabric Heat Loss: Heat lost through walls, roof and glass
- Air Heat Loss: Heat lost due to infiltration
- Total Heater Load: Includes 20% safety margin
- Heater Capacity: Final selection value
🛠 Practical HVAC Notes
- Always use winter design outdoor temperature
- Higher glass area = higher heater capacity
- For cold regions, increase safety margin
- Room-wise calculation gives best accuracy
