Evaluating Domestic Water Heater Performance for NY Homes NYSERDA Agreement 15606

Transcription

1 Evaluating Domestic Water Heater Performance for NY Homes NYSERDA Agreement Report 1 Laboratory Test Results Deliverable 7a November 2013 Submitted to: NYSERDA 17 Columbia Circle Albany, NY Submitted by: Hugh I. Henderson, Jr. Jeremy Wade CDH Energy Corp. PO Box Bingley Rd Cazenovia, NY (315) Edward A. Bogucz Chris Straile Syracuse Center of Excellence 727 Washington St. Syracuse, NY [Type text]

2 Contents Tested Water Heaters... 1 Laboratory Test Results CURRENT DOE Draw Profile... 2 Laboratory Test Results New PROPOSED DOE Draw Profile... 6 Standby Losses Future Plans [Type text]

3 Tested Water Heaters The laboratory setup has separate eight stations to test nine DHW systems Based on the Task 2 report (July 2012) we recommended that the hot water heaters listed in Table 1 be included in this test. Station 4 has a single-tank solar system piped in series with a conventional electric tank. Testing to date has treated these two units as a single system. Table 1. DHW Units in Laboratory for Side-By-Side Testing Station Technology Classification Manufacturer and Model EF or SEF Input and Size 1 st Hour Rating 1 1 st flr GAS-STD Standard Gas Storage A.O. Smith GCVX MBtu/h 50 gal 93 gal/h 2 1 st flr HE-PVNT Non-condensing Power Vent Gas Storage Rheem 43VP40SE MBtu/h 40 gal 73 gal/h 3 4 th flr SOLAR Flat Plate, Glycol Solar Hot Water Rheem SOLPAK 3.2 RS120-64BP 3.2 SEF 4.5 kw 120 gal 99 gal/h 4a 4 th flr SOLAR-DRAIN Drain-Back Solar Hot Water Wagner & Co SECUSOL gal na 4b 4 th flr ELECT-STD Standard Electric Storage A.O. Smith ECT kW 52 gal 60 gal/h 5 4 th flr TANKLESS Condensing Gas Tankless Rheem RTGH-95DVLN MBtu/h 4.8 gpm 6 4 th flr HE-COND HE Condensing Gas Storage A.O. Smith Vertex GDHE-50 Not rated by EF (96% efficiency) 100 MBtu/h 50 gal na 7 4 th flr HYBRID Hybrid HE Small Storage A.O. Smith NEXT HYB-90N not rated by EF (90% efficiency) 100 MBtu/h 25 gal na 8 4 th flr HPWH Heat Pump Water Heater GE GEH50DEEDSC kw 50 gal 65 gal/h CDH Energy Corp. 1 November 2013

4 HW Use (gal) Laboratory Test Results CURRENT DOE Draw Profile All the units were operated using the same water use profile. After the initial shakedown and verification in March and early April 2013, the systems started to operate on April 10 with the standard draw profile used in the DOE test procedure: six draws one hour apart; each draw is 10.7 gallons at 3 gpm (64.2 gallons per day). Figure 1 and Figure 3 shows that there was still variations in the water draws and total use per day that were caused by problems with the flow limiters. Table 2 shows that the average water use for each system ranged from 60 to 75 gallons per day. 14 Water Use: 72.4 gal/day 04/11/ : 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0: Figure 1. Water Draw Profile Imposed on Water Heaters CURRENT Draw Profile Figure 2 and Table 2 summarize the conversion efficiencies measured for each system and compare them to the rated EF. The standard efficiency gas tank (Gas-STD) and the high-efficiency power vented unit (HE-PVNT) are both in very good agreement with the measured EF. The conversions efficiency for the tankless water heater (TANKLESS) is also within 5% of the rated EF. The measured efficiency for the heat pump water heater (HPWH) actually exceeds the rated value by 5%. This water use profile did not induce any resistance element operation. The solar system (SOLAR) had an effective conversion CDH Energy Corp. 2 November 2013

5 efficiency of 2.3 for this spring period, which is lower than the SEF from the OG-300 rating from SRCC. The glycol-filled drain back system (SOLAR-DRAIN) was not properly commissioned in this period so it did not function as expected. The combined tankless unit with a small tank (HYBRID) locked out whenever the HPWH ran. This problem was fixed around the April 26, but the overall efficiency only changed slightly. The HYBRID system efficiency was still well below expectations. Similarly the high efficiency, condensing tank was 10% below the expectations (given as thermal efficiency). Table 2. Summary of Water Heater Performance CURRENT DOE Draw Profile (April 10 to May 20) Notes: Solar system has a Solar Energy Factor (SEF) instead of an Energy Factor (EF). Similarly, the High Efficiency Condensing Tank (HE-Cond) and the Hybrid unit (with a small tank) are rated as commercial units with a thermal efficiency (TE) instead of an EF. The other test conditions were not fully consistent with those specified in the DOE Test Procedure, but were close. For instance the inlet water temperature is specified as 58 F in the procedure. The actual lab test conditions, shown in Figure 4, vary slightly from that specified value. Similarly, the supply temperature from the tank is specified as 135 F. Most systems were near that point with the exception of the SOLAR-DRAIN and the TANKLESS units. CDH Energy Corp. 3 November 2013

6 Conversion Efficiency (-) Conversion Efficiency (-) 6 04/10/13 to 05/20/ SEF=3.2 SEF=3.1 3 EF= April May Gas STD HE-PVNT Solar Solar Drain Tankless HE-Cond Hybrid HPWH 1.0 TE=0.96 EF= /10/13 to 05/20/13 TE= EF= EF= April May Gas STD HE-PVNT Solar Solar Drain Tankless HE-Cond Hybrid HPWH Figure 2. Comparison of Measured Conversion Efficiency and Expected Energy Factors CURRENT Draw Profile CDH Energy Corp. 4 November 2013

7 Useful Energy (MBtu/day) Supply Temperature (F) HW Use (gal/day) 80 04/10/13 to 05/20/ April May /10/13 to 05/20/ April May Gas STD HE-PVNT Solar Solar Drain Tankless HE-Cond Hybrid HPWH Figure 3. Daily Hot Water Use and Supply Temperatures CURRENT Draw Profile 04/10/13 to 05/20/ Inlet Temperature (F) Gas STD HE-PVNT Solar Solar Drain Tankless HE-Cond Hybrid HPWH Figure 4. Useful Energy vs. Inlet Water Temperature CURRENT Draw Profile CDH Energy Corp. 5 November 2013

8 HW Use (gal) Laboratory Test Results New PROPOSED DOE Draw Profile The new PROPOSED test procedure from DOE developed more realistic draw profile made up of 12 events with a total water use of 64.2 gallons. This Normal Use profile is shown in Figure 5 below (the slightly different use for Unit 1 on this day is due to flow limiter variations). This profile was imposed on all the systems starting in September 18. The supply temperature was also lowered to 120 F in order to reflect more realistic use patterns (except the SOLAR system, which remained at 135 F). 20 Water Use: 65.2 gal/day 09/19/ : 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0: Figure 5. Water Draw Profile Imposed on Water Heaters PROPOSED Normal Use Draw Profile CDH Energy Corp. 6 November 2013

9 Table 3 and Figure 7 show the measured conversion efficiency for these slightly different operating conditions. Similar overall performance was observed with this new use pattern. The SOLAR system conversion efficiency is slightly lower since the period is slightly cloudier in early fall. The lockout problem with the HYBRID system was corrected in this period so the efficiency is slightly higher but still is much lower than the value implied by the thermal efficiency. Table 3. Summary of Water Heater Performance PROPOSED Normal Use Draw Profile (September 18 to October 31) Notes: Solar system has a Solar Energy Factor (SEF) instead of an Energy Factor (EF). Similarly, the High Efficiency Condensing Tank (HE-Cond) and the Hybrid unit (with a small tank) are rated as commercial units with a thermal efficiency (TE) instead of an EF. This water use profile did not induce any resistance element operation for the HPWH unit. CDH Energy Corp. 7 November 2013

10 Conversion Efficiency (-) Conversion Efficiency (-) 6 09/18/13 to 10/31/ SEF=3.2 SEF=3.1 3 EF= September October Gas STD HE-PVNT Solar Solar Drain Tankless HE-Cond Hybrid HPWH 1.0 TE=0.96 EF= /18/13 to 10/31/13 TE= EF= EF= September October Gas STD HE-PVNT Solar Solar Drain Tankless HE-Cond Hybrid HPWH Figure 6. Comparison of Measured Conversion Efficiency and Expected Energy Factors PROPOSED Draw Profile CDH Energy Corp. 8 November 2013

11 Useful Energy (MBtu/day) Supply Temperature (F) HW Use (gal/day) 80 09/18/13 to 10/31/ September October /18/13 to 10/31/ September October Gas STD HE-PVNT Solar Solar Drain Tankless HE-Cond Hybrid HPWH Figure 7. Daily Hot Water Use and Supply Temperatures PROPOSED Draw Profile 09/18/13 to 10/31/ Inlet Temperature (F) Gas STD HE-PVNT Solar Solar Drain Tankless HE-Cond Hybrid HPWH Figure 8. Useful Energy vs. Inlet Water Temperature PROPOSED Draw Profile CDH Energy Corp. 9 November 2013

12 Standby Losses From May 22 to June 27, 2013 the water heaters in the laboratory ran in standby mode with no hot water use. This provided an indication of the standby losses from each system. The air temperature on 1 st floor (for DHW1 and DHW2) was 70 F. The air temperature for the other units on the 4 th floor was 75 F. The measured standby losses are summarized in the table below. The figures show the variations on losses over the period. Table 4. Summary of Water Heater Standby Losses Unit Gas Use (MBtu/day) Electric Use (kwh/day) DHW1 GAS-STD ~10 - DHW2 HE-PVNT DHW6 HE-COND DHW7 HYBRID 8.3 Not measured DHW8 HPWH CDH Energy Corp. 10 November 2013

13 Daily Gas Use (MBtu/day) DHW1 (AO Smith GCVX ) For DHW1, the conventional, natural-draft water heater, the standby losses showed much more fluctuation than expected. The variation may indicate significant differences in the amount of draft induced through the unit. The average was 23.2 MBtu/day while the most common minimum value was just over 10 MBtu/day. The hot water set point was F. 80 DHW AVG = May June 2013 Figure 9. Daily Standby Gas Use for DHW1 CDH Energy Corp. 11 November 2013

14 Daily Gas Use (MBtu/day) DHW2 (Rheem 43VP40SE2) For DHW2, the power vented unit with an EF of 0.67, the standby losses were 6.3 MBtu/day. The hot water set point as about 130 F. 12 DHW AVG = May June 2013 Figure 10. Daily Standby Gas Use for DHW2 CDH Energy Corp. 12 November 2013

15 Daily Gas Use (MBtu/day) DHW6 (AO Smith Vertex Unit) Average gas use is 6.9 MBtu/day with no water use. Standby losses reported on AHRI certificate are 499 Btu/h, or 12.0 MBtu/day. Tank set point is 135 F. 15 DHW AVG = May June 2013 Figure 11. Daily Standby Gas Use for DHW6 CDH Energy Corp. 13 November 2013

16 Daily Gas Use (MBtu/day) DHW7 (AO Smith Hybrid Unit) Tank set point is 130 F. Average gas use is 8.3 MBtu/day with no water use. Standby losses reported on AHRI certificate are 378 Btu/h, or 9.0 MBtu/day. 12 DHW AVG = May June 2013 Figure 12. Daily Standby Gas Use for DHW7 CDH Energy Corp. 14 November 2013

17 Daily Electric Use (kw h/day) DHW8 (Geospring GEH50DEEDSC) Standby losses are 0.69 kwh/day. The hot water set point was 130 F. 1.0 DHW AVG = May June 2013 Figure 13. Daily Standby Electric Use for DHW8 CDH Energy Corp. 15 November 2013

18 Future Plans We continue to refine the flow limiters and water flow solenoids to provide a more accurate and consistent water use pattern. Plumbing unions were added in September 2013 to provide easier access to the flow limiters for repair and cleaning. Once consistent operation is demonstrated with the Normal Use profile, we plan implement the Low Use and High Use patterns from the proposed DOE test procedure. The performance under these different use profiles will be compared. The Wagner Solar System (SOLAR-DRAIN) is still not operating as expected. We will continue to work with the manufacturer to make this system operate as expected. The solar systems show clear seasonal variations. The HPWH also shows some variation with indoor humidity and temperature. We will continue to test these systems to ensure we have data from a range of operating conditions across the year. CDH Energy Corp. 16 November 2013