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Heat Pump Sizing Formula:
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Underfloor heat pump sizing calculates the required heating capacity (in kW) for an underfloor heating system based on the floor area and heat load factor. Proper sizing ensures efficient operation and comfort.
The calculator uses the basic heat pump sizing formula:
Where:
Explanation: The calculation determines the kilowatt rating needed for a heat pump to adequately heat the specified area.
Details: Correct heat pump sizing is crucial for energy efficiency, system longevity, and maintaining consistent comfort. Oversized units short-cycle, while undersized units run continuously.
Tips: Measure your floor area accurately. The heat load factor depends on insulation, climate, and floor construction (typically 50-75 W/m² for well-insulated homes, 75-100 W/m² for average insulation).
Q1: What's a typical heat load factor for underfloor heating?
A: Most residential underfloor systems use 50-100 W/m². Well-insulated homes may use 50-75 W/m², while older homes may need 75-100 W/m².
Q2: Should I add a margin to the calculated size?
A: Professional installers often add 10-20% margin for extremely cold days, but modern heat pumps can modulate output so exact sizing is often best.
Q3: Does floor covering affect the calculation?
A: Yes, thick carpets may require slightly higher factors, while tile floors may work with lower factors due to better heat conduction.
Q4: How does ceiling height affect sizing?
A: Standard calculations assume 2.4-2.7m ceilings. For higher ceilings, increase the factor by 5-10% per additional 0.5m.
Q5: Can this calculator be used for whole-house heat pumps?
A: This calculates just for underfloor systems. Whole-house sizing requires additional factors like wall insulation and window quality.