How Can Cold Water Make Hot Water?


UCSD Researchers Team Up with local San Diego Inventor to Develop Technology to Create Hot Water from  Cold


Improves the efficiency of water heating by as much as 50% to 100%


San Diego, CA – April 4, 2013


Testing at the University of California, San Diego has confirmed a potential new source of free energy for heating water – your homeÕs cold water. Most households use 3 to 4 times as much cold water as hot water and in temperate climates the cold water averages over 70¼F throughout the year, which is 15¼ to 20¼F warmer than it needs to be. Using a prototype consisting of a small water-to-water heat pump to extract heat from the water in a 20-gal cold water tank and deliver it to a typical 50-gal water heater, researchers lead by Dr. Jan Kleissl of the Mechanical and Aerospace Engineering Department were able to demonstrate the systemÕs efficiency using the standard water heater test for the Energy Star¨ rating.


To test real-world performance, three systems were installed in homes in coastal, mountain and desert climates to determine the effects of different incoming cold water temperatures. Also, each system was monitored for a year to compare performance in various seasons.


The results show that, at the prototype stage, this design improves the efficiency of water heating by as much as 50% over to the current water heating efficiency leader, the air-source heat pump water heater (like the GE Geospring). Refinements are expected to increase that to 100%, putting it on par with the best solar water heaters with no rooftop panel required.


Testing of the patented system (7,827,814) was funded with a grant from the California Energy Commission. The inventor, Hal Slater of San Diego CA, is currently seeking a manufacturer or VC partner to commercialize the product for single-family and multifamily applications.


Press Inquiries:

Mark Shapiro

SRS Tech PR - "Media Relations for the Connected World"

+ 1 619 249 7742

Twitter - @SRSTechPR

Skype - mark.shapiro5


Patent Inquiries:

Hal Slater

(619) 248-3592