The California Energy Commission has passed final approval for the update to Title 24 Energy Efficiency Building Codes. This presentation shows some of the new updates.
Under Hot Water, page 15, it shows “Demand Controlled Recirculation” as a prescriptive baseline. This code will go into effect on January 1st, 2014.
Architects, Engineers, Certified Energy Plans Examiners, LEED-AP’s, and Energy Efficiency Consultants should get familiar with how they systems work and how to meet the future codes. Feel free to contact us for any design assistance on your projects.
What is demand controlled recirculation?
Demand controls on domestic hot water circulation systems turn off the circulation pump when it is not needed, effectively reducing thermal heat losses from the recirculation loop, resulting in a decrease in the boiler fire time and, consequently, a reduction in overall natural gas consumption. Demand controls also save on electricity by minimizing pump motor runtime.
A demand controlled pump automatically turns off when the hot water circulation loop is at target temperature and when there is no demand for hot water. Even when there is a demand for hot water, if the supply loop is still at the target temperature, the pump will remain off. This method of distribution keeps the hot water from continuing to circulate, preventing wasteful heat loss and pipe deterioration, as previously stated. As soon as someone uses hot water and activates the demand sensor (flow switch), the control box then reads the water temperature in the return line through its temperature sensor (thermistor). If the hot water is already at target temperature, the demand controls will keep the pump off thus saving substantial amounts gas and electricity consumption. If the hot water is below target temperature, demand controls will immediately turn on the pump and deliver hot water to the fixture.