In our article we calculated what is the cost of a 5 minutes long shower. We also estimated how much does it cost to heat 1000 litres of water.
The 12kW instantaneous water heater, with a water temperature increase of 30°C, has an efficiency of 5.8 l/min. A standard shower spout needs about 5-6 litres of water for proper functioning. The water temperature at the inlet to the heater is around 10°C in summer. With these assumptions, we can calculate, e.g. how much a 5-minutes long shower cost. You will also find out how much it costs to heat a 1000l of water.
How much does one shower cost?
For a 5-minute long shower, under the above assumptions, we will use 29 litres of water and 1.02kWh of electricity. If you multiply 1.02 per cost of 1kWh of electric energy in your location, you will find our how much is one shower. If we use a single-phase heater (e.g. EPJ.P Primus 5.5 kW), then the cost will be even less. The efficiency of EPJ.P.Primus is 2.7l/min (+30 °C ). Then we will use only 14 litres of water and 0.47kWh of energy for a 5-minute shower. Multiply 0.47 per cost of 1kWh in your location and you will know the approx. cost of one shower. It is worth to mention that a fine spray spout is a much better selection for a single-phase heater. It provides better comfort of use with hot water yields, e.g. Primus 5.5 kW.
How much does it cost to heat 1000 litres of water?
The calculation of cost for heating 1000 litres of water is much reliable for many people. The water temperature at the inlet to the heater is about 10°C . While the optimal temperature of the bathwater is about 38-40°C, i.e. the heater should heat the water by 28-30°C . The efficiency of the 21kW heater, with an increase in water temperature by 30°C , is 10.1 l/min. This device heats 1000 litres of water in 99 minutes or 1.65 hours consuming about 34.5 kWh. Multiply 34.5 per cost of 1kWh in your location to know how much you will per for electricity to heat 1000l or 1 m3 of water. It is worth to know that one person consumes about 1.5 m3 of hot water per month.
Electric water heating is not expensive
The above calculations prove that heating water with electricity is not expensive. Instantaneous water heaters are optimally selected for the planned demand for hot water. Besides, we place it near water collection points. Thanks to this, there is no loss of hot water and energy-related to water storage. It is typical e.g. in a tank and transporting water over a long pipe. The operating costs of a continuous flow heater are lower than the costs for hot water in many housing associations.