C AT E E P R E S E N TAT I O N – D E C E M B E R 1 8 , 2 0 1 3 D I A N A D . G L AW E , P H D , P E , L E E D A PE N G I N E E R I N G S C I E N C E D E PA RT M E N T

COLLECTING & USING CONDENSATE ON SITE 

ENERGY ESTIMATES FOR SAN ANTONIO

• Extraction, processing, and distribution of potable water 1,939 KWh per million gallons

• Wastewater Treatment 2,232 kWh per million gallons

(Source: Barker, Bill. 2010. “Energy Consumption Associated with Water.” Environmental Policy Office City of San Antonio.)

1 million gallons

4,171 kWh

CARBON FOOTPRINT ESTIMATES FOR SAN ANTONIO

• 6.8956 x 10-4 metric tons CO2 produced per kWh *

• 4,171 kWh per million gallons potable water

(Source: Environmental Protection Agency, Emissions and Generations Resource Integrated Database. <www.epa.gov/egrid> )

1 million gallons

2.84 metric tons

ENERGY WATER NEXUS

• Saving water saves energy• Saving energy reduces carbon footprint

(It works the other way around too…… saving energy saves water)

ON SITE WATER SOURCES

• Condensate• Rainwater• Cooling tower blowdown• Reverse osmosis wastewater• Gray water• Etc.

CONDENSATE

Water that collects on a cool surface because the temperature of the surface is below the point at which moisture in the air forms liquid droplets (i.e. dew point)

AIR HANDLING UNIT (AHU)

(Source: San Antonio Condensate Collection and Use Manual for Commercial Buildings. Pending publication)

HOW MUCH CONDENSATE?

HOW MUCH CONDENSATE?

Example: 154,440 sq ft (727 ton) applied engineering and technology building measured condensate with predictions (747,290 gallons/yr)

(Source: San Antonio Condensate Collection and Use Manual for Commercial Buildings. Pending publication)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

Measured Gallons8 gpd per ton0.3 gph per ton0.1 gph per ton 0.6 gph per 1000 sq ft0.5 gph per 1000 sq ft10 gpd per 1000 sq ft3 gpd per 1000 sq ft

Gallons c

ondensate

AWE

Bryant &

Ahmed

SAWS

CONDENSATE WATER QUALITY?

(Source: EPA WaterSense at Work. EPA 832-F-12-034)

CONDENSATE WATER QUALITY - METALS

• Condensate is slightly acidic• Metals picked up along the flow path (ppm)

• Cooling coils• Drain pan • Drainage pipe • Reservoirs/Tank• Pumps• Fixtures

CONDENSATE WATER QUALITY - MICROORGANISMS

• Legionella bacterium is primary concern for condensate use if aerosol is possible

• Comingling with other water sources adds microorganism possibilities

• No fecal matter expected in condensate alone

CONDENSATE APPLICATIONS

• Cooling tower• Irrigation• Car washing• Water features• Process water• Toilet flushing

CONDENSATE (ALONE) APPLICATIONS

• Cooling tower make-up water is BEST application• Low initial cost• Easy implementation• Cool and pure water a plus • Low maintenance

Example: Building producing 224,511 gallons per year. Cost to install retrofit system for cooling tower makeup water was $2,272 materials (pipes and pumps) plus $750 labor. SAWS rebate 50%. Incremental investment $1,511. Payback period 16 months. No water treatment beyond that already existing for cooling tower water. No overflow and no storage requirements. Maintain air seal and pump (if applicable).

(Source: San Antonio Condensate Collection and Use Manual for Commercial Buildings. Pending publication)

TREATMENT TRAIN WHEN COMMINGLED

• Depends on reclaimed water source(s)• Depends on reclaimed water application

(Source: Adapted from Mechell et. al, Rainwater Harvesting: System Planning. 2010)

EFFECTIVE DESIGN – DRAIN LINE AIR SEAL

(Source: San Antonio Condensate Collection and Use Manual for Commercial Buildings. Pending publication)

STANDARD P-TRAP

• Isolates air handling unit• Minimizes pipe wet time• Maintenance access point• Trap configurations

• Draw-thru trap• Blow-thru trap

• Standard traps incur • High maintenance• High failure rate

(Source: Brusha, Ronald F. “Condensate Traps for Cooling Coils.” HPAC Engineering, Oct 2001)

ALTERNATIVES TO STANDARD P-TRAP

P-trap with additions

Condensate pump in drain pan

Pneumatic air seal*P-trap

(Source: San Antonio Condensate Collection and Use Manual for Commercial Buildings. Pending publication)

* Patented by Trent Technologies, Inc. (CostGard)

EFFECTIVE DESIGN AND OPERATION– AUTOMATED MONITORING

• Drip pan overflow alarm• Condensate meter data collection• Make-up water meter data collection• Water quality sensors in treatment train• Make it difficult for system failures to go

unnoticed

OPERATION AND MAINTENANCE -SCHEDULED MAINTENANCE PROGRAM

• Start with commissioning during installation!• AHU: air filter, cooling coils, drain pan• Drain seal• Piping, pumps, and valves• Storage Tank: overflow and makeup water control• Backflow valve inspection• Water treatment filters, lamps, etc.• Water quality tests

CONDENSATE ON SITE USE

• Reduces city’s energy use• Reduces city’s carbon footprint• Potential quick return on investment for facility • Potential to alleviate drought restrictions on site

QUESTIONS

Diana D. Glawe, PhD, PE, LEED APAssociate ProfessorTrinity UniversitySan Antonio, TX 78209

dglawe@trinity.edu210-999-7515 ?