Choosing an instant water heater

Choosing an instant water heater

Find out first how much warm water you currently use before purchasing an instant water heater. An Eco showerhead will use less water than a rain shower.

  • ECO showerhead: 7 to 10 litre per minute

  • Normal showerhead: 10 to 15 litre per minute

  • Rain shower: 20 to 25 litre per minute

We hope this information will help you in choosing the right instant water heater. Do bear in mind that you require sufficient power for an instant water heater. Obviously the instant water heater will only use power when it is heating. To give you an example a house is fused for 1x25A. A more recently built is fused for 1x35A. For power current usually it is 3x25A or in newer buildings 3x35A.

  • 3500W (3.6kW) is almost 16A. So one group of 16A.

  • 5000W (5kW) is almost 22A and can therefore not fit on a standard group

  • 11kW is usually 3-phase electricity of 3x16A

  • 18kW is always 3-phase electricity of 3x26A

  • 24kW is always 3-phase electricity of 3x35A

Bear in mind that the power mentioned above is for the instant water heater alone. So if you use your cooker, blow-dryer or television at the same time that will add the power you consume. As the name implies you get instant hot water. The outgoing water temperature depends on the water temperature coming in. In the UK the average water temperature is between 10 and 15 degrees celsius. In warmer countries, such as Turkey and Greece your instant water heater will obviously give out warmer water.

It is important to mention that the instant water heater will give slightly less water than you are normally used to. There are instant water heaters being sold with a shower head that will not match your expectations. Below an overview of the litres per minute from the various instant water heater models and how much that approximately is mixed with cold water. Mixed water coming from your faucet will be around 38 degrees celsius. If you have a rain shower we advise against using an instant water heater.

  • 3,5kW instant water heater : approximately 2 litre per minute, 40 degrees celsius unmixed;

  • 3,5kW instant water heater: approximately 2,5 litre per minute, 38 degrees celsius mixed;

  • 5 kW instant water heater: approximately 2,5 litre per minute, 46 degrees celsius unmixed;

  • 5 kW instant water heater: approximately 3,5 litre per minute, 38 degrees celsius mixed;

  • 11kW instant water heater: approximately 6 litre per minute, 40 degrees celsius unmixed;

  • 11kW instant water heater: approximately 7 litre per minute, 38 degrees celsius mixed;

  • 18kW instant water heater: approximately 7 litre per minute, 50 degrees celsius unmixed;

  • 18kW instant water heater: approximately 9 litre per minute, 38 degrees celsius mixed;

  • 24kW instant water heater: approximately 9 litre per minute, 50 degrees celsius unmixed;

  • 24kW instant water heater: approximately 12 litre per minute, 38 degrees celsius mixed;

Purpose:

  • 3,5kW: under the washbasin in the toilet;

  • 5 kW: For washing your hands in the garage;

  • 11 kW: For shower and kitchen if you are okay with a not too powerful water jet. Comparable to an old gas boiler;

  • 18 kW: Shower and bath. This model will provide you with a reasonably comfortable. Filling a bath will slightly take longer than with a cv boiler;

  • 24 kW: Shower and bath. Comparable to a CV combi boiler;