1. California Energy Commission Funded Research Project
Energy Research on Improving the Balancing and Mixing of Domestic Hot Water
California Energy Commission Funded Research Project

2. About Enovative Los Angeles based water and energy efficiency company
Product development and manufacturing in the field of hot water control systems
Independent and government funded research
Water and energy retrofit services

3. CDHW Energy Flow
Graph courtesy of California Utilities Statewide Codes and Standards Team, “Multifamily Central DHW and Solar Water Heating”, Oct. 2011

4. Research Focus
Unbalanced Recirculation Loops- The problem of recirculation loops not having proper balancing valves to equalize water flow rates and temperatures throughout the network of pipes.
Fixture Crossover- The problem associated with faulty faucet and shower fixtures, which allows cold water to infiltrate the hot water piping

5. What is unbalanced Circulation?

6. What is Crossover?
When faulty mixing valves cause uncontrolled mixing between the hot and cold water pipes
Can potentially happen at any point where hot and cold water pipes meet
May be asymptomatic

7. What is Crossover?
Without Crossover
With Crossover

8. Mixing Valve and Cartridge
Crossover due to failed mixing cartridges:
Other causes of crossover may include: mop sinks, washing machine connections,

9. Symptoms of Crossover Fluctuating and unsteady water temperatures
Long hot water wait times
Lukewarm water temperatures, never hot
Different hot water temperatures at different fixtures in the dwelling unit
No hot water
Hot water in the toilet
No symptoms, water is an acceptable temperature

10. Other Sources of Crossover
Kitchen spray nozzles
Mop sinks
Laundry machines
Any fixture that keeps the hot and cold in an “open” circuit

11. Research Goals Identify the frequency of crossover issue
Develop method to test and identify it
Evaluate ideal fix to reduce or eliminate issue
Savings potential
How to detect Crossover?
How wide spread is the issue?
How much energy is wasted?
Potential for energy and financial saving?

12. Experimental Setup at Lab Facility

16. Temperature Differential Method
The Tests
Method
Scenario 1 Result
Scenario 2 Result
Verification
Notes
Pressure Gauge Method
Detected
Not Detected
Method Validated
Quickest, building-level test
Water Flow Method
Building-level and pinpointing detection possible
Eatherton Method
Pinpointing detection possible, non-invasive
Temperature Differential Method
N/A
Invalid
Can be indicative of crossover
Pump Control Method
Discarded, but may reveal crossover symptoms
Water Meter Method
Only possible in some buildings

17. How To Test For Crossover
Pressure Gauge Method
Eatherton Method
System for detecting crossover within a building
Will not pinpoint exact location of crossover, only discover if happening somewhere in the building
Can be quickly and easily performed on any building
System for detecting crossover at the fixture point
Helps determine if a particular mixing valve is failing and needs fixing
Can be easy or difficult to conduct, depending on how the fixture is set up

18. Pressure Gauge Method

19. Accessing the Mixing Valve

20. Conducting the Eatherton Method

22. Initial Results
Out of 100 buildings tested so far, about half have tested positive for crossover in the building
Level of severity has ranged from mild to severe
Potential for energy savings may be substantial

23. Crossover Case Study Largest multifamily building in San Diego
40 stories
(2) large boiler systems feeding (6) loops with electric re-heat tanks
Each loop services roughly 100 units

24. Crossover Case Study- San Diego
Pressure Regulating Valves for the hot and cold water piping for one of the loops

25. Project Next Steps
Baseline data collection
Tracking 10 building with existing crossover issues, ranging from units. Monitoring temperatures, run times and pressure
Repair crossover
After 2-3 months baseline data collection, replace all faulty mixing valves or install check valves to eliminate all crossover flow in the building
Post-fix data collection
Post-fix data collection and calculate any resulting efficiency gains

26. Dwelling Units
= Spring loaded check valve
HW Supply
HW Return
Pump
City Gardens Apartments
Total # of Units = 23
Number of Stories = 2

28. Preliminary Findings
First test sited demonstrated approximately 18% reduction in water heater energy use
Tenants informed us water was much hotter and consistent than prior to the fix
Would suggest that is now possible to lower tank temperature as temperatures are more steady
Additional savings to be had from implementing recirculation pump controls

29. Project Future Tasks
Task 5 – Recommendations for codes & standards update (August, 2016)
Task 6 – Technology Transfer (December, 2016)
End of Project (June, 2017)

30. Gabriel Ayala Enovative gabe@enovativegroup.com
Thank You
Gabriel Ayala
Enovative