Domestic hot water

The aim of this article is to provide technicians and engineers with the basic principles for designing and calculating domestic hot water production and distribution systems, whether for individual or collective equipment. It is based on the book entitled "ECS. L'eau chaude sanitaire dans les bâtiments résidentiels et tertiaires. Design and calculation of installations". As this book points out, there are many publications on this subject, but the information is scattered and sometimes even contradictory.

Sizing a DHW system (as we'll call it from now on throughout this document) is not based on deterministic rules. Needs generally fluctuate over time and from place to place, with user behaviour and expectations varying widely, and are sometimes difficult to define. This article is not intended to lay down sizing rules, which would be risky given fluctuating energy and equipment costs.