Monitoring Field Performance of Residential Geothermal Heat Pumps Brought to you by Manitoba Hydro s Earth Power Program Presented by: Rob Andrushuk, C.Tech. Date: November 18, 2008
Today s presentation topics Part 1 Why monitor heat pump performance? Part 2 What information did we gather? Part 3 How did we monitor the seasonal efficiency of a ground source heat pump? Part 4 Who, when, and where? Part 5 Results
Part 1: Why monitor heat pump performance?
Why monitor heat pump systems? Manitoba Hydro promotes ground source heat pump technology and the public looks to us for energy saving information
Why monitor heat pump systems? ARI certified efficiency information already available, but is for steady state efficiency at set operating conditions and does not include all system losses Require better information on the actual efficiencies of heat pumps installed in our climate Require information on desuperheater performance in a heating dominated climate
Other possible benefits Determine best practices: Loop design Heat pump sizing Desuperheater Duct design
Part 2: What information did we gather?
System seasonal efficiency Seasonal Coefficient of Performance (SCOP) of the heat pump over a heating season Seasonal Energy Efficiency Ratio (SEER) of the heat pump over a cooling season Domestic hot water energy savings provided by the desuperheater
Part 3: How did we monitor the seasonal efficiency of a ground source heat pump?
Equipment Energy meter 8 channel logger (digital, analog, and amperage)
Power consumption Data logger monitors power consumption of: Whole house Heat pump compressor Fan Ground loop pump Auxiliary heater Desuperheater pump Domestic water heater
Equipment Current transformers
Energy provided from or to the loop Temperature probes are installed on the loop supply and return to the heat pump A flow meter is installed on the loop The temperature difference is logged when the heat pump is operating Energy = mass flow rate x specific heat x temperature difference
Equipment Flow meter Resistance Temperature Detectors (RTD)
Hot water heater energy supplied to home Monitor hot water consumption and temperature difference Add stand-by losses for water heater Utilized water meter with pulser and temperature probes
Part 4: Who, when, where?
Who, when, where? 10 single detached residential homes Monitored since 2006 Still monitoring most sites Located in various regions of Manitoba Various heat pump manufacturers and installers Various loop designs All with desuperheaters
Overview of monitoring sites (noted in red)
Part 5: Results
2007 Heating Season SCOP of 2.8 (2.9 without auxiliary heat) Average heat pump operated 2,242 hours with 8,664 starts 5,719 Degree-Days (average year is 5,778 DD) Ground loop provided an average of 17,409 kwh of heat Auxiliary heater provided 1% of annual heating
Chart #1: Field Monitored COP Versus Manufacturer's CSA/ARI COP 3.4 3.6 3.7 3.6 3.8 3.9 3.7 3.59 2.7 2.7 3.2 2.3 2.9 3.3 2.8 1.8 3.5 3.2 3.8 3.0 3.2 2.8 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 1 3 5 7 9 Weighted House # Average Field Monitored SCOP CSA/ARI COP Rating SCOP or COP
Weighted Average Annual Entering Water Temperatures (degrees Fahrenheit) 50.0 45.0 40.0 35.0 30.0 25.0 20.0 15.0 10.0 5.0 0.0 44.9 35.1 34.6 39.5 36.1 38.0 35.6 32.8 38.8 34.2 36.0 Well to Well Lake Loop Horizontal Loop Vertical Loop Horizontal Loop Horizontal Loop Vertical Loop Vertical Loop Horizontal Loop Vertical Loop Average Loop Type Temperature (F)
50.0 45.0 40.0 35.0 30.0 25.0 20.0 15.0 10.0 5.0 0.0 44.2 Minimum Entering Water Temperature 29.2 29.0 32.1 33.3 30.5 27.2 24.1 32.3 27.43 29.5 Average Lake Loop Horizontal Loop Vertical Loop Horizontal Loop Horizontal Loop Vertical Loop Vertical Loop Horizontal Loop Vertical Loop Ground Loop Type Well to Well Temperature (F)
Compressor Consumption per 10,000 btu of heat delivered Electricity draw (Watts) 1000 900 800 700 600 500 400 300 200 100 0 595 834 632 839 671 579 702 918 619 691 693 1 2 3 4 5 6 7 8 9 10 Average House #
250 200 150 100 50 0 109 62 Fan Power (Heating) 205 149 145 150 232 67 149 139 77 48 9 10 average ARI/CSA 13256 3 4 5 6 7 8 House # 2 1 Watts /10,000 btu heat output
350 300 250 200 150 100 50 0 Ground Loop Pump Power (Heating) 275 299 330 158 161 121 105 124 98 103 163 29 1 2 3 4 5 6 7 8 9 10 average ARI/CSA 13256 House # Watts / 10,000 btu of heat delivered
2007 Cooling Season Actual average SEER of 13.5 Average CSA/ARI EER rating of 16.2 Average heat pump operated 216 hours with 1,102 starts 2007 Degree-Days Cooling was 199 (average year is 186 DD Cooling) Average heat pump consumed 791 kwh of electricity 2007 heating/cooling ground load ratio was 5 to 1
16.4 10 13.3 16.76 Actual SEER in 2007 versus ARI/CSA EER Rating 24.5 18 12.5 16.1 14 17.5 11.9 15.7 8.5 14.2 16 16.5 13.0 19.9 9.9 13 19.8 16 2 3 4 5 6 7 8 9 Weighted Average 12.2 1 30 25 20 15 10 5 0 House # SEER CSA/ARI EER Rating SEER/EER
Domestic hot water (DHW) Average savings of 18% 86% of the savings occurred in heating mode Reduced average annual electricity usage by 613 kwh Two desuperheater pumps failed during the test period Domestic hot water heaters operated at temperatures lower than manufacturer s recommendations Water heater temperature required adjustment in the spring and fall when only one storage tank was used
Net Annual DHW Energy Savings 1200 1109 1142 Energy Saved (kwh) 1000 800 600 400 200 650 227 454 204 733 839 816 617 0 0 1 2 3 4 5 6 House # 7 8 9 10 Average
Questions? Personal contact information: Rob Andrushuk, C.Tech. Manitoba Hydro Mechanical Systems Specialist Phone: (204) 477-7716 E-mail: randrushuk@hydro.mb.ca