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Heat Only Boiler Sizing Formula:
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Heat only boiler sizing calculates the required kilowatt (kW) output needed to adequately heat a specific volume of space, taking into account the desired temperature difference between indoor and outdoor conditions.
The calculator uses the standard heat loss formula:
Where:
Explanation: This formula estimates the heat loss through walls, windows, roof, and ventilation, helping determine the appropriate boiler size for efficient heating.
Details: Correct boiler sizing is crucial for energy efficiency, comfort, and system longevity. An oversized boiler cycles frequently, reducing efficiency, while an undersized boiler cannot maintain comfortable temperatures.
Tips: Measure the volume of your space accurately. For ΔT, use the difference between your desired indoor temperature and the typical winter outdoor temperature in your area (usually 20-22°C indoor minus -1 to -3°C outdoor).
Q1: What is a heat-only boiler?
A: A heat-only boiler (also called regular or conventional boiler) provides central heating only and works with a separate hot water cylinder.
Q2: How accurate is this calculation?
A: This provides a basic estimate. For precise sizing, consider insulation levels, window types, and building orientation. Professional assessment is recommended.
Q3: What factors affect the heat loss coefficient?
A: Insulation quality, window-to-wall ratio, building age, and construction materials significantly impact the actual heat loss.
Q4: Should I add a safety margin?
A: Typically add 10-20% to the calculated kW for safety margin, especially in older properties or extreme climates.
Q5: Can this be used for combi boilers?
A: This calculation focuses on heating requirements only. Combi boilers also need to consider hot water demand, which may require additional capacity.