The sizing method used by the Ecosizer was developed in 2020 by Ecotope, Inc. This method, referred to as the Ecosizer method, provides a significant improvement to the ASHRAE sizing method for water heating systems. The Ecosizer method accounts for hot water production during periods of peak demand from building occupants. This approach allows the system to be sized smaller than the ASHRAE method.

Water heating system sizing is to specify heating capacity and hot water storage volume needed to meet peak hot water demand on the design day, which is usually the day with coldest entering cold water temperature. The Ecosizer method provides the minimum heating capacity and storage volume needed to meet this anticipated peak hot water demand.

The Ecosizer provides a sizing curve (Primary Sizing Curve) to determine required HPWH heating capacity and storage volume according to HPWH and storage equipment characteristics. Users need to select HPWHs according to their heating capacity under the design-day weather conditions (usually the coldest day). Note that most HPWHs have defrost cycles and therefore a derated output capacity when ambient temperatures are below 50°F.

We’d love to get your feedback on the Ecosizer. Bug reports, feature suggestions, and other thoughts can be submitted via our feedback form.