The power consumption of electric showers in the maximum heating setting is about 5.5 kW for 120 V and 7.5 kW for 220 V. The lower costs with electric showers compared to the higher costs with boilers is due to the time of use: an electric shower uses energy only during the water flow, while a boiler works many times a day to keep a larger quantity of standing water hot for use throughout the day and night. So electric showers may save energy compared to gas central heaters. A 20 minute bath by an electric shower can cost about US$0.10, but the same bath using water from a gas heater can cost three times as much. This difference can be larger where the electricity is cheaper than the gas supply, or in tropical countries where the maximum power consumption is required only during the cold seasons.