BTU/hr to Watts Converter

HVAC equipment specification: converting US-rated heating and cooling equipment (BTU/hr) to SI power units (watts or kW) for international specifications.

Energy efficiency calculations: translating thermal loads to electrical power requirements.

Building energy modeling and LEED documentation requiring SI units.

In residential and commercial HVAC equipment selection, the BTU/hr-to-W conversion is the primary bridge between the US heating and cooling capacity specification (BTU/hr) and the electrical input specification (W or kW), which determines the electrical service size, the breaker rating, and the operating cost.

A 3-ton (36,000 BTU/hr) residential air conditioner with a SEER rating of 16 has an average power draw of 36,000 / 16 = 2,250 W (2.25 kW) during cooling operation, requiring a 30-amp 240V electrical circuit.

The conversion also allows the calculation of the seasonal energy use: a 3-ton AC running 1,200 hours per year in cooling mode at SEER 16 consumes 2.25 × 1,200 = 2,700 kWh/year, costing about $350/year at $0.13/kWh.

Heat pump performance is rated in COP or HSPF in the international market and in HSPF in the US market, with the conversion between the two based on the BTU/hr-to-W factor: a COP of 4.0 means 4 W of heat delivered per W of electrical input, equivalent to 4 × 3.412 = 13.65 BTU/hr heat per W of input.

Data center cooling systems are now commonly specified in kW per rack (5–40 kW) and total kW of IT load, with the conversion to BTU/hr for the cooling capacity (10 kW = 34,121 BTU/hr = 2.84 tons) at the cooling system design boundary.

Renewable energy systems (solar thermal collectors, geothermal heat pumps) are specified in kW of thermal output per the EU Renewable Energy Directive, with the conversion to BTU/hr for US-spec equipment (a 5 kW_thermal solar collector is 17,061 BTU/hr at peak solar irradiance, or about 1.4 tons of equivalent cooling).

Process heating and boiler efficiency calculations use the BTU/hr-to-kW conversion at the fuel input vs heat output boundary: a 1 million BTU/hr (1 MMBTU/hr) natural gas boiler with 85% thermal efficiency delivers 850,000 BTU/hr of useful heat, equal to 249 kW, requiring about 293 kW of gas input at the burner.

Refrigerated warehouse and cold storage facility design uses the conversion between refrigeration capacity (tons of refrigeration or kW of cooling) and the heat of respiration of stored products (fruits, vegetables, and other fresh produce generate heat that must be removed by the refrigeration system, with the heat of respiration given in BTU/hr per ton of produce and requiring the conversion at the refrigeration system sizing step).