Since we’ve been looking at air conditioning lately…

Watts = BTU / EER
Amps = Watts / Volts
Volts = Watts / Amps

The Voltage will normally be 230 if the Watts are higher than 1000 (generally units higher than 10000 BTU), otherwise 110. For amperage calculations, the rated value seems to use either 100 or 110 Volts for 110 Volt units and 225 Volts for 230 Volt units.

To calculate the cost of running, calculate the total kW h and multiply by the rate.
For example:

6 hours/day * 30 days * 950 Watts = 171,000 W h = 171 kW h
171 kW h * 0.10 $/kW h = $17.10

(BTU = British Thermal Units)
(EER = Energy Efficiency Ratio)

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