Drain Water Heat Recovery

Transcription

1 Drain Water Heat Recovery SRC Test Facilities Chris James M.Sc. EIT Saskatchewan Research Council

2 Outline Background on Drain Water Heat Recovery (DWHR) Testing Facilities at SRC Performance of DWHR units (Field Testing) Conclusions Contact Information

3 Background on DWHR DHW consumption second highest energy use: ~20-30% of energy consumed showering tends to be the largest part of DHW heating (50-70%) Recover heat that normally goes down the drain to preheat supply water Replace a portion of existing drain stack

4 Background on DWHR No moving gparts Made from copper No mixing of potable/drain water 3 major manufacturers in Canada Installed cost ~ $600 - $1200

5 Testing Facilities at SRC Commissioned i in 2007 Developed to test manufactured units for performance (effectiveness, pressure drop) Operates in balanced flow configuration Potable water flow rate = drain water flow rate Most effective configuration Results from testing to determine level of rebates under the ecoenergy Retrofit - Homes Effectiveness Grant Amount 30.0 < < 41.9 $95 42 $165

6 Test Facility Water temperatures t and flow rate are controlled Can accept up to a 60 long DWHR unit of 3 or 4 diameter The effectivess of the unit at 9.5L/min (2.5 gpm) is reported for rebate purposes

7 Testing Conditions Operating Flow Rates Balanced Flows of 5,8,11,14 L/min (1.3, 2.1, 2.9, 3.7 gpm) Measured using a pulse meter Operating Temperature Cold Water Temp: 8 ± 2 C (46 ± 4 F) Drain Water Temp: 36 ± 2 C (97 ± 4 F) More important is the difference between DW/CW Measured using thermocouples

8 Test Results

9 Test Results

10 Test Results rop (psi) Ave 60 Ave 40 Effectiveness Pressure Drop fectivenes ss (%), Pr ressure D Eff 0

11 Field Testing Results Results from three residential houses in Saskatchewan 2 houses are heated with solar/electric systems Average incoming water temperature of 8 C (46 F) Average of 4 people/household

12 Factor 9 House, Regina SK Factor 9 house uses 9 times less energy than the average existing home (circa 1970) in Saskatchewan (~9900 F HDD). Water use of 50% of the average usage from rain water harvesting, conserving. Active solar thermal panels heat a 2350L tank in the basement. Watercycles DX-3058, 42% effective installed

13 Factor 9 House, Regina SK Water Heating System DWHR Plumbed to shower cold water and electric water heater Solar Thermal Panels which heat a large storage tank (41%) Electric Water Heater for any additional heating (37%) Recovered Heat from DWHR (22%) (% contribution to DHW)

14 Factor 9 House, Regina SK Energy Recovered over 1 year of Monitoring: 772 kwh Electrical Cost of ~$0.10/kWh Annual Savings: ~$80

15 Dumont Residence, Saskatoon SK Space and water heating done by solar thermal panels and electric water heater. DWHR added to conserve energy and reduce incoming cold water temperatures. DWHR plumbed to shower cold water and electric water heater. Watercycles DX 3060 Annual contribution: 520 kwh ~ $52 Savings Electrical cost of $0.10/kWh

16 Dumont Residence, Saskatoon SK Water hea ating Energy (kj) For Period Shown: Electric 880kWh - 47% Solar 702kWh - 38% GFX 275kWh - 15% Weekly Water Heating Energy by Source 1026 Main Street Electric Solar GFX Date ( )

17 Winder Residence, Saskatoon SK Power-Pipe R3-30 ~One Month of Monitoring i 3000 L (800 gal) of potable water run through DWHE. Plumbed to cold water on shower and toilet tanks (less sweating) Average Heat Transfer: 1.2 kw/shower Measured Peak Heat Transfer: 3.9kW Expected Energy Saving: 336 kwh/yr Expected Savings: ~$10/yr (2.1 /kwh)

18 Conclusions DWHR units can be good systems for saving energy/money No moving parts/maintenance Efficiently recovers heat that s going down the drain Grants are a good incentive to reduce payback period 2 to 3x annual payback Testing has been performed on 9 units since inception

19 Thank you Contact Information Chris James Saskatchewan Research Council (