Water heating sizing guide for installers

Ariston has introduced a comprehensive guide to its vented, unvented and instantaneous electric water heaters, outlining which models are best suited for a range of domestic and light commercial applications throughout the UK.

It is important to properly size a water heater to meet the needs of a business or household and ensure optimum efficiency.

Ariston’s water heating guide makes it simple to identify which product is best suited for a project, by cross referencing the types of outlet with the intended levels of use. For example, it identifies that for a single basin with a light level of water usage, the wall-mounted, 5-litre Piccolo would be adequate. Similarly, for heavy use applications looking to feed three wash basins or a kitchen sink, 30-litre capacity Andris Lux or Andris Lux Eco water heaters should be installed.


For projects involving wash basins, products such as the Andris Lux, Andris Lux Eco and Andris R can be fitted, as can the Piccolo or Aures Slim Multi instantaneous electric water heater. The guide identifies which capacity unit should then be used, depending on light, medium or heavy levels of water use.

Similarly, as the number of wash basins increases, the size of the water heater used has to follow suit. So, whereas a 6-litre product could cater for a single basin at medium usage, two basins would require a 10-litre Andris Lux or an Aures Slim Multi instantaneous unit for the same level of use.


Although the products already mentioned can feed a kitchen sink if required, once there are multiple sinks being used frequently, units with capacities over 30-litres are recommended. Ariston’s Velis Evo, Velis Evo Wi-Fi and Pro1 Eco models are best suited here, with their respective 45-litre and 50-litre versions suitable for medium use or their larger 80-litre counterparts handling heavy water usage with ease.


This requires 45 to 50-litre units so, once again, the Velis Evo Wi-Fi and Pro1 Eco are recommended, moving up to the 80-litre versions should multiple showers and basins need filling. Additionally, as water usage increases, for example in multiple occupancy properties, Ariston recommends using the 80-litre models of these platforms, or using the 100-litre version of the Pro1 Eco for applications where showers and basins will be used in succession.


Finally, for applications with a bathtub, either Ariston’s 80-litre Velis Evo Wi-Fi or 100-litre Pro1 Eco are recommended as the average bath holds 80 litres of water, with at least 75% being hot) a large capacity unit is required – especially if it will be required to supply other outlets, such as a kitchen sink, at the same time as the bathtub.

Installers should also note that different models can be combined for different areas of a property or business. For example, a restaurant could utilise a Pro1 Eco storage water heater in the kitchen to cope with high levels of usage, whereas smaller areas with less water demand, such as washrooms, could be fitted with Aures Slim Multi instantaneous water heaters. Similarly, an office could have a small Andris Lux Eco beneath its kitchen sink, while a larger capacity Velis Evo Wi-Fi electric storage water heater supplies its shower and washrooms.

Victoria Gutierrez, marketing manager at Ariston, adds: “Choosing the correct electric water heater will undoubtedly result in cost and energy savings for end users; however, the size of electric water heater is determined by how many people are going to be using it, as well as the reheat times and frequency of use. Our new guide simplifies the product selection process so, whatever size or capacity is required, it will be easy to find the water heater in our portfolio best suited for the project in hand.”

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