The research found multiple ways to detect crossover, verified detection methods, andassessed the practicality of using a method in the field. The research team applied thesedetection methods on approximately 100 multifamily buildings, and results show thatcrossover may be in as many as 52% of the multifamily buildings. Recommendations include:install check valves before shower valves or on risers feeding shower valves; install isolationvalves around shower valves; require pressure balance, thermostatic, or combinationpressure balance/thermostatic shower valves with an integral check stops. Cross-over was considered for the 2022 Title 24 standards but not incorporated.
This research project quantified the energy and water impacts of crossover and unbalanced recirculation loops in domestic hot water systems associated with multifamily buildings and identified best practices and tools for identifying and pinpointing these issues. Crossover occurs when hot water goes into the cold water line, and vice versa. Preventing, identifying and repairing crossover issues can reduce energy, water and other waste (less wasted water going down the drain) in central hot water systems.[br /]
Identifying and correcting crossover results in greater customer/tenant satisfaction since they will receive hot water sooner.
Research results estimate 16% gas savings and up to 30% water savings due to elimination of cross-over. This will result in benefits to multifamily residents receiving hot water sooner at the fixture, and landlords and occupants can benefit by lower costs.
Significant natural gas savings will reduce greenhouse gas emissions. Water savings will eliminate water waste. Water savings of 30% can be very beneficial in communities that are facing water shortages and may not have a reliable water source.
Key Project Members
Enovative Group, Inc.