We will also look into some examples of how costly it is to run 8 kW – 30 kW tankless heaters at 100% heating output: Per hour. On average, $1,06 for a small 8 kW heater and $3,96 for a big 30 kW heater. Per month. Between $18,55 and $69,03 (more in the table below), with an average for a 4 person family of $43,94 per month. Per year. App Vay Tiền Nhanh.

how much is 18 kwh