Heat Pump Size Formula:
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Definition: This calculator determines the required size (in kW) of an air source heat pump based on your property's heat loss and the system's coefficient of performance.
Purpose: It helps homeowners and installers properly size heat pumps for UK properties to ensure efficient operation and avoid undersizing or oversizing.
The calculator uses the formula:
Where:
Explanation: The heat loss is divided by the COP to determine the heat pump size needed to maintain comfortable temperatures.
Details: Correctly sizing your heat pump ensures optimal efficiency, reduces running costs, extends system lifespan, and maintains comfort levels.
Tips: Enter your property's heat loss (from a heat loss calculation) and the expected COP (typically 2.5-4.0 for UK systems). All values must be > 0.
Q1: How do I find my property's heat loss?
A: A qualified energy assessor can perform a heat loss calculation, or you can use online tools with your property details.
Q2: What's a typical COP for UK heat pumps?
A: Most modern air source heat pumps have a COP between 3.0 and 4.0 under UK climate conditions.
Q3: Why does COP affect the size needed?
A: Higher COP means more efficient heat production, so a smaller unit can meet your heating needs.
Q4: Should I add a buffer to the calculated size?
A: It's common to add 10-20% capacity for extremely cold days and to account for potential calculation uncertainties.
Q5: Does this calculator account for hot water needs?
A: No, this calculates space heating requirements only. Add 0.5-1.5kW if the heat pump will also provide domestic hot water.