DHW cylinders are judged according to their standby losses, in other words the amount of heat that they lose to the surrounding area over time.

Weishaupt's new WAS 140 Tower-Eco, WAS 150 Eco, and WAS 200 Eco DHW cylinders were developed with an eye to the minimisation of these standby losses. Their optimised thermal insulation, comprised of vacuum insulation panels and polyurethane foam, keeps the energy where it belongs – in the cylinder. The standby losses of the new Eco cylinders are between 0.84 and 0.99 kWh over 24 hours and thus about 40% lower than conventionally insulated DHW cylinders.