A.O. Smith sizing: a unique water heater selection program

Selecting the right hot water system for a new building or a renovation project is complex. A.O. Smith has developed a unique calculation program called ‘’Sizing program’’ to make this exercise easier. By completing a number of consecutive steps, an advice for a specific hot water appliance will follow. Solar recommendations consist of an integrated system advice; non solar recommendations refer to a specific hot water appliance.

The A.O. Smith Sizing program, accessible online 24 hours per day, takes into account all relevant factors that influence this choice. This makes it an ideal tool to quickly and correctly find the most suitable hot water system for your project location.


For more than 40 years, A.O. Smith Water Products Company has been a leading global manufacturer and supplier of quality water heating equipment. The extensive A.O. Smith product range includes both large industrial and small residential water heaters. A few years ago we added sustainable energy solutions to the existing product range of gas-fired, indirect and electric appliances. The renewable segment includes several renewable solar systems.

Appliance selection

In new development and renovation projects many factors directly or indirectly affect the type of hot water system, such as application, water usage, draw-off intensity, temperature settings, number of taps, fuel type, geographic location and available space. Important characteristics that make the A.O. Smith solar systems a suitable option for new development and renovation projects, are low NOx emissions of ? 30 p.p.m. (dry – air free, NOx class 5) and whisper quiet operation (<45 dB(A) at 2m distance from roof duct). Our solar thermal energy systems and BFC high efficiency water heater heaters perform with considerably higher (system) efficiency than comparable installations in the market.

All relevant factors affecting the choice for the right appliance are taken into account in the A.O. Smith Sizing program. The A.O. Smith Sizing program is a tool to structure all this information. The program provides a choice between HE and conventional appliances, as well as a choice between a solar system and a conventional hot water system. Furthermore, in case of a solar system both the collector roof construction (roof build on, roof build in or flat roof consoles mounting and wall mounted sets) as well as the desired collector surface can be chosen. For solar applications all relevant parts are included in the recommended installation. The program immediately displays the hot water requirements, specifying water needs in liters and the required energy in Gigajoule/year and kWh/year. In case of a solar application 2 options will follow, specifying the possible solar contribution and the expected annual savings from this installation. Finally, the advice can be exported to a Word document.


The A.O. Smith website, www.aosmith.co.uk, includes a link to our water heater selection program in the chapter ‘Sizing program’. The Sizing program has a series of detailed questions regarding your project location. Based on your input data, the program provides you with an installation advice. When all steps are followed, an advice for a hot water installation will be provided. If the program is not able to calculate a suitable solution for your project location it will provide you with an A.O.Smith alternative. Discrepancies to the initial requirement will also be provided.

The staff of the A.O. Smith Technical Support Group will be pleased to provide additional information. The Technical Support Group is available weekdays from 8.30hrs until 17.00hrs CET via e-mail tsg@aosmith.nl and via telephone +31 40 2942551.

You might also like