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HomeMy WebLinkAboutJuneau Water Source Heat Pump Program 1984JUNEAU WATER SOURCE HEAT PUMP PROGRAM FINAL REPORT ALASKA POWER ADMINISTRATION February 1984 JUNEAU WATER SOURCE HEAT PUMP REPORT Introduction The Juneau Water Source Heat Pump Program is sponsored by Alaska Power Admin- istration (APA). Two water-to-air residential heat pump installations were installed under this program to provide information on the performance of these systems in the Juneau area. APA will not prepare any further reports on this study, however, data will continue to be collected and will be avail- able at APA headquarters. : History This study is a follow-up to an earlier program sponsored by APA, Alaska Electric Light & Power Company (AEL&P), and Glacier Highway Electric Associa- tion (GHEA) which evaluated eight air-source heat pump installations in the Juneau area. The earlier study was completed in August 1982 and concluded that air-source heat pumps were technically and economically viable as a heating mechanism for use in Southeast Alaska and were preferable to electric resist- ance heat since they used energy sources more efficiently. Specific information on that study can be obtained in the JUNEAU HEAT PUMP PROGRAM FINAL REPORT August 1982, which can be obtained from APA, AEL&P, and GHEA offices. The overall efficiency of the air-source heat pumps was over double that of electric resistance systems, however, there were certain periods of cold weather which caused the efficiency to decrease. Since Juneau has an abun- dant source of near-constant temperature seawater, the question was posed as to whether a water-source heat pump could use this heat source effectively thereby maintaining near-constant efficiencies through the colder periods. The present program involves two heat pump installations which use seawater as the source of heat. The objective is to determine if the units will operate satisfactorily in the temperature regime prevalent in seawater in the Juneau area. This temperature -- about 45 degrees Fahrenheit -- is the low end of the recommended range for water-source heat pump applications. Current Program Data The two water-source heat pump systems consist of one which has been oper- ational since November 1981 at the Ken Ryals' residence on Lena Cove and the second which has recently become operational at the Jack Schoenmann resi- dence at Indian Cove. Both systems are very similar as they use Northrup VWTA-65 (71,000 BTU) units which use seawater as the heat source. The following description of the Ryals' system would also be similar to the system in the Schoenmann residence. A closed 500-foot loop of 1% inch PVC pipe runs from the home down to the beach to a 300-foot pipe coil buried below low-tide level. The pipe then completes the loop back to the house where the water-source heat pump is located. Propylene glycol fluid (nontoxic antifreeze) inside the PVC pipe absorbs heat from the ground and seawater, carrying it back to the house. This fluid is pumped through the coil by a one-horsepower Jacuzzi pump. Table 1. summarizes home construction characteristics and heat pump design specifications for the Ryals' system being evaluated. Since the Schoenman installation is new and no data are available, only the Ryals' data are being analyzed. Juneau Weather Data Heating degree days for 1982 and 1983 are shown by month on Figure 1. along with the 25-year average. The 1982 heating season was cooler than normal with January being 20 percent cooler and February 18 percent cooler than the long term average for those respective months. The 1983 heating season has been warmer than the average with January being 19 percent warmer and February 10 percent warmer than the long term average. Operating Performance Electric Energy The first of each month, the utility electric service meter used for billing was read at the same time as a meter connected to the heat pump only. These readings may not coincide with the utility billing cycle as they are timed to agree with the monthly weather data for use in the computation of the heat pump output and performance. Monthly energy use data for the Ryals' heat pump system and total home electric use was tabulated in Table 2. Heat pump energy use was 17,471 kwh/year in 1982 and 9,418 kwh for the first nine months in 1983. Total home electric use was 34,620 kwh/year for 1982 and 17,986 kwh for the first nine months of 1983. The heat pump system accounted for 50 percent of the total electric use in 1982 and 52 percent in 1983. cop Data obtained from monitoring were used primarily to determine the COP of each unit. This was done by comparing the amount of energy required to operate the heat pump with the amount of energy output (heat). Energy out- put was determined by evaluating the heatload characteristics of the struc- ture and heat source gains other than the heat pump (such as passive solar, wood stove, electric lights, and appliances, etc.). Table 3. presents the monthly data for heat input, heating load, heat pump output, and the resulting COP for the heat pump. The seasonal performance factor (SPF) is also computed. Examination of this table reveals COPs ranging from 1.36 in February 1982 to 3.57 in June 1983 with the average COP being 2.53. The overall SPF for the residence was 2.20. Two months were not used in calculating the average or the SPF, as noted, due to higher COPs than can be expected. These two months were July 1982 and July 1983, and solar gain was the probable reason for the resulting high calculated COPs. Figure 2. graphically compares the monthly COPs and the monthly heating degree days. It shows that the efficiency of the heat pump generally increases as the outdoor temperatures increase. This was expected to some degree since the seawater temperature is warmer during the summer months, however, it was believed that the seawater would have temperature changes at a more moderate rate than the air temperature changes. Since the water source TABLE 1. HOME AND WATER SOURCE HEAT PUMP SYSTEM CHARACTERISTICS IN IRINA IGN ING RG Re RG NA NR RD UN RR NN ND I RR NR NG NN NEO OR EN EN Design Living Temp Home Area Homeowner Deg F Characteristics (sq. ft.) System Model No. III IGN IG ID NNN A NNN NIN NGG NG NGL NR AR NE EE I MN Re Re Ryals 35-150 Wood-frame, 1 story 1,350 Northrup R-19 Wall S-Ton VWTA-65 R-28 Ceiling 30% Window area CAPACITY BALANCE PT. HEATING SYSTEM COST I I I I GG IR A RDI GG EIN A ROR I Ee Ne a ee a ea ee a ee ee (71,000 Btu/hr) 45 deg F $14,830 Tyalsi Figure l. JUNEAU AIRPORT HEATING DEGREE DAYS + 7 ts ! +Z ! ! | te | Vi | te | 1 & i tho 1 in | pe tE4 | +I! ! Pin | tz! | tu ! ! | th toe | 128 ! 1 = | ‘0 | +h | | ! +! 1 1 1 ! thi | | 1 | thy | tEN 1 1 I +on | ie ! / i eee i 1 oil bh bee ae ie, ee ee ee fe ee $e ee ee op ee eee ewe me we Gearon 8 8 S S S 8S 8 S 3 8 8 8 wo % S i + a a a a Lesernce O4eTM¢vs Oonun APA -— OCT 1983 (o) 25-Year Average HDD LEGEND -- (x) Actual HDE TABLE 2. ELECTRIC CONSUMPTION KEN RYALS RESIDENCE Total Home Heat Pump Month (kwh) Ckwh) PRN NNN NNN Dec 3,967 2, 787 1982 Jan 5. 344 2, 087 Feb 4,596 4,014 Mar 4,542 2,143 Apr 4,610 1,762 May 2,376 1,284 Jun 1,118 508 Jul 1,053 228 Aug 1,436 428 Sep 1,850 536 Oct 2,247 1,104 Nov 3,013 1,511 Dec 2,435 1, 866 cece SS SSSS>==> 34, 620 17,471 1983 Jan 3,917 2, 662 Feb 3,455 1,583 Mar 2,522 1,392 Apr 2,232 1,171 May 1,596 689 Jun 1,569 301 Jul 921 178 Aug 1,305 449 Sep 2,038 993 19, 555 9,418 ryals2 WATER SOURCE HEAT PUMP ANALYSIS KEN RYALS RESIDENCE 623 Btu/Hr/Degree Heat Load Month nA Dec 1982 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1983 Jan Feb Mar Apr May Jun vul Aug Sep t23=£1] (4)=(3] CS3=Cil {6]=(5] tii t2) Total Home Ckwh) (MMBtu) ANN 13. ANN 3. 967 5,344 4,596 4,542 4,610 2.376 1,118 1,053 1,436 1,850 2.247 3,013 2.435 3.917 3,455 2.522 2.232 1,596 1,569 921 1,305 2,038 18. 15. 15. 15. ~ roared SPOUUNDHW DONT PWD 54 ts) Cé3 Non-. eating (kwh) (MMBtu) NN 4. NNN 1,180 3,257 582 2,399 2,848 1,092 610 625 1,008 1,314 1,143 1,502 569 1,255 1,872 1,130 1,061 907 1,268 743 856 1,045 PADPONNY OO» UNNAVVOOD 03 ARN 69 69 69 69 69 69 69 69 69 69 69 69 69” 69 69 69 69 69 69 69 69 69 Temperature Inside Outside (MMBtu) (MMBtu) RRNA 27 “Table 3. C113 Heat Pump NNNOOPNNE Pe V NONDONNNS c.0.P. NAR 1. 83 80 36 79 50 11 76 74 * 26 43 80 81 54 75 28 91 47 o9 57 x 3,413 Btu/kwh x 3,413 Btu/kwh -€3] 3] c4] Heat Pump (kwh) (MMBtu) RRR NN 2. 787 9.51 2. 087 7.12 4,014 13.70 2.143 7.31 1,762 6.01 1,284 4.38 508 1.73 228 0. 78 428 1.46 536 1.83 1,104 3.77 1,511 5.16 1,866 6.37 2, 662 9.09 1,583 5.40 1,392 4.75 1,171 4.00 689 2.35 301 1.03 178 0.61 a4o 1.53 993 3.39 99.90 [8IJ=Average monthly temperature C93=(C€73-[8]) x 623 Btu/hr/degree x 24 hours x days in month -5) €103=£9) -(f6) «x €113=£101/(£4) # - Excluded from Seasonal Performance Factor (SPF) calculations. cio] co] Heat Heating Pump Load Output NN 19. 47 17.45 25.49 19.94 19. 68 18. 68 17.15 13. 06 13.91 9.05 11.12 9.26 5.83 4.79 5.10 3. 69 6.49 4.77 8.52 6. 28 12.51 10. 56 17.05 14.48 17.15 16.18 18. 08 15.94 15.49 12. 30 15.76 13. 83 11. 66 9.85 8.81 7.26 5.83 3. 67 5.56 4.29 6.49 5.03 9.42 7. 64 265.91 220.00 y APA 10/83 ryals Heat Pump COP 5.0 4.0 3.0 2.0 1.0 FIGURE 2 HEAT PUMP COP'S & HEATING DEGREE DAYS WARMER 225 350 475 600 725 850 975 1100 Heating Degree Days 1225 1350 1475 1600 1725 COOLER temperature was not closely monitored, it is difficult to determine how rapidly changes in the seawater temperature occurred. Recent temperature monitoring during start-up of the Schoenmann heat pump indicated water temperatures could vary as much as 10 degrees between low-tide temperatures and high-tide temperatures. The pipe coil containing the circulating fluid is apparently influenced considerably by the air temperature due to the relatively shallow water depth covering it. Annual Operating Cost The records for the last 12 months available, October 1982 through Sept- ember 1983, were analyzed to determine the annual heating costs for the heat pump as well as alternative electric resistance heating and fuel oi] heating systems. The costs calculated were based on the actual cost of electricity and fuel oi] during the period examined, and no additional comparisons were done under different price structures. Table 4. shows these cost comparisons for the water source heat pump, an air source heat pump, an equivalent electric resistance heating system, and an equivalent fuel oil system. The total costs for the year indicate the water source heat pump annual cost of $809 would be about 25 percent less than the cost for an air source heat pump at $1,026; about 60 percent less than the cost of electric resistance heating costs of $2,108; and about 45 percent less than the cost of fuel oil heating costs of $1,436. Conclusions Previous studies and programs completed by APA and two utilities in Juneau, and a similar program in Ketchikan have shown that air source heat pumps are technically and economically feasible for heating in Southeast Alaska. This current study on water source heat pumps shows that these units can perform even better with resulting lower operating costs. The average monthly COP for the water source unit was 2.53 while the average COP for all the air source units was 2.05. The seasonal performance factor (SPF) of the water source unit was 2.2 which indicates that it would be more than twice as efficient as electric resistance type heating systems. The annual operating cost for this heat pump would be 60 percent less than costs for a system using electric resistance heating and 45 percent less than a system using fuel oi]. Although the annual operating costs for the water source heat pump may be lower than for any of the alternative heating systems mentioned, the initial installation cost is much higher. A cost of nearly $15,000 is about double the cost of an air source heat pump and about triple the cost of a fuel oil system. No attempt was made in this study to determine the levelized costs for the various heating systems which would make a comparison which includes all costs over the long term. Water source heat pumps appear to operate quite satisfactorily in the Juneau area using seawater as a source for heat. No extraordinary main- tenance problems have been noted as yet, and they appear to operate quite economically when compared to alternate heating systems. No installations presently use groundwater as a heat source in this area, and it is not known whether a water source unit would operate at acceptable levels with the low Heat Outpu Month MMBtu ARAN Oct Nov Dec van Feb Mar Apr May Jun Jul Aug Sep 41 /2 73 74 45 46 47 10. 14. 16 15. 12 13. 47 Measur Based Based Based Based Based Fuel surcharge of 2.95 cents/Kwh added based on prior month use Nu eoyn g Equivalent Electric Resistance Kwh /4 RRNA AAS 3,094 4,243 4,741 4,670 3,604 4,052 2,886 2,127 1,075 1,257 1,474 2,238 s nen! 165. 227. 253. 250. 192. 216 154. 113. 86. 137. 122. 186. /2 ed 62 11 77 01 92 91 49 87 68 57 62 24 2, 108. Table 4. JUNEAU WATER SOURCE HEAT PUMP STUDY HEATING SYSTEM COST COMPARISON Pump Water Source Air Source t Heat Pump Heat Pump Kwh /1 $ /2 Kwh /3 $ /2 ON NR RRR RRR 56 1,104 59.10 1,517 61.19 48 1,511 80. 88 2.257 120. 80 18 1,866 99.89 3,269 175.01 94 2, 662 142. 50 2, 883 154. 32 30 1,583 84.74 2,310 123. 66 83 1,392 74.51 2,026 108. 46 gs 1,171 62. 68 1,552 83. 06 26 689 36. 88 890 47. 64 67 301 24. 32 462 24.70 29 178 24.04 454 24.29 03 449 37.36 590 31.56 64 993 82. 62 969 51. 87 eesscs= sesssee 809. 52 1,026. 57 ed. on: 5.3 cents/Kwh for Oct. thru May; 8.0 cents/Kwh for June thru Septi plus tax on erage COP for air source units on 3,413 Btu/Kwh. on 138,000 Btu/gallon with 65% furnace efficiency on $1.05/gallon plus tax - 00 Equivalent Fuel Oil Gal. /5 $e /é RNR 118 124.85 161 171.19 180 191.29 178 188. 45 137 145. 42 154 163. 51 110 116.45 81 85.83 41 43.39 48 52.23 56 61.23 85 93.01 eessscs 1, 436. 86 APA 1/84 Tyals3 temperatures prevalent in Juneau area groundwater. APA had originally Plan- ned on including a groundwater unit in this program, however, the manufacturer had expressed some question about the capability of the unit to function at optimum levels.