Heat Pump Water Heaters: A Key Energy Technology for ...€¦ · Heat Pump Water Heaters: A Key Energy Technology for California Passive House California April 2018 Danny S. Parker

FLORIDASOLARENERGYCENTER— AResearchInstituteoftheUniversityofCentralFlorida

AResearchInstituteoftheUniversityofCentralFlorida

HeatPumpWaterHeaters:AKeyEnergyTechnologyforCalifornia

PassiveHouseCaliforniaApril2018

DannyS.Parker


HeatPumpWaterHeaters(HPWH):WhatAreThey?HowDoTheyWork?

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WhatYou’lllearn• Whatareheatpumpwaterheaters?• Howwelldotheyworkinthelaboratory?• Howwelldotheyworkinthefield?

– Whatdescribesbestunits?– Whataresomenon-waterheatingissues/advantages?

• Howdotheycomparewithanaturalgaswaterheater?• WhataretheimpactsonGreenhouseGases?• Whatareimpactsoncost?• Whatarenewtechnologies?

– Improvedcompressors&UEF– PVassistedHPWH


HotWaterSystems(HWS)LaboratoryFSEC:Cocoa,Florida

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FloridaSolarEnergyCenter– HotWaterSystemsLaboratory

EvaluatedMostPopularHotWaterSystems

2012EvaluatedHybrids

2014MoreHPWH’s/Hybrids

PVHPWH2016- Present

Plumber’snightmare!


Averaged1-YearPerformanceofWaterHeatersand1stGen.HPWHinLaboratory(Cocoa,FL)

6

0.85

0.56

0.71

2.27

0.00 1.00 2.00 3.00

Dailyefficiencies (COP)

HeatPumpWH

NatGasTankless

NatGas40Gal.

50Gal.Electric

[2.35]

[0.83]

[0.91]

[0.59]

AnnualPerformance EnergyFactororUEF

Typicaloperatingefficienciesforstandardwaterheaters

ModernHPWH

FirstGenerationNos.NowUEF(likeCOP)of3.7orgreater


50Gal.HeatPumpWaterHeaterEfficiency

7

0

0.5

1

1.5

2

2.5

3

3.5

4

40 50 60 70 80 90 100

COP

AverageDailyHWSLabInteriorTemperature(F)

WhereHPWHlocatedmatters!


SimulatedPerformanceofHPWHinU.S.

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WhereHPWHlocatedmatters!


WhatCanwelearnfromthefield?60measuredFLhomes;red=hotwater

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HeatPumpWaterHeaters• Dependablesavingsvs.electricresistancewater

heaters,in10homeschangedout• 80gal.models:4+personhouseholds• 68%overallsavings(5.3kWh/day)• 80gal:74%savings(7.6kWh/day)


NortheastHPWHStudy(MassachusettsandRhodeIsland)

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HPWHCapacity(gal) RatedEFAvg.COP %SavingsGeneralElectric50 2.35 1.82/1.61 44-55%AOSmith 60/80 2.33 2.12 58%StiebelEltron 80 2.51 2.32 61%

GEUnits=10,Stiebel Eltron =2,AOSmith=2

CostEffectiveness;simplepayback5.7yrs(avg.)- Rangeof3.2- 10.5yrs@$0.17/kWhOnlyfourHPWHleftatdefaultsetting120F(others122– 140F)


HowDoesthisComparetoPG&E?• GasWaterHeatingmajorpartofPG&EGHGemissions• WaterheatingisBIG:90%ofPGEcustomers=gaswaterheat

• Gasusefrom2009RASSsurvey195therms or3,169kWhifelectric• Ourspreadsheetestimates203therms/2885kWhforSanJose

• 4.6millionrescustomers=4.72millionTonsCO2 peryear!• Whatareoverallcost &Carbon Impacts?

0

500

1000

1500

2000

2500

Nat.GasTank NatGas:Tankless ElecResistance HPWH PV_HPWH

AnnualCarbonImpact&$CostforWaterHeating

lbsCO2/yr $Dollars/yr


LessonslearnedfromMulti-FamilyHousingInstallations

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ServiceDoorcommonexteriorhallway

TransferGrillsfacingkitchenandlaundry

HPWHinconfinedsmallvolumecloset(<100ft3)


HPWHSurveyResponseFiveMulti-FamilyComplexes

• 720HPWHUnitsinstalledinMulti-familyhomesthroughoutFlorida

• Generallyhi-acceptance• IsolatedcomplaintsFannoise• Somecomplaintsof

insufficienthotwater• FewaskhigherT’stat set

+5deg(125⁰F)

• OnecasereportedhavingturnspaceheatONbecauseofcoldairbyHPWH

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Other:QuarterlymaintenanceforairFilter,Drainagecheck


LaboratoryTestingtoRe-createFieldinstallationsinconfinedspace

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00.10.20.30.40.50.60.70.80.91

40

45

50

55

60

65

70

75

80

0 3 6 9 12 15 18 21 24

Cond

ensate(P

int)

ClosetTe

mpe

rature(F)

orRH(%) RH

ClosetT

Cond.Pints

15-minutedataintervals


HPWHConfinedinClosetPerformanceAnalysis

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Days Avg. kWh/day

Avg. COP

Avg. Inlet (F)

Avg. Outlet (F)

HPWH in conditioned lab 6 2.050 2.64 74.78 118.47

HPWH in conditioned + confined space (92.5 ft3) 7 2.342 2.30 74.21 117.49

Percent increase of electric use

14% 0.292 Volume Draw

Percent COP reduction 13% 50 gal./day


HPWHcoolsthespacewherelocated

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Canprovidefreecoolingorslightincreasestoheatingiflocatedinside

-Likesmallroomairconditioner- Running2hrs inthemorning

Potentiallyfreecoolinginsummer

Otherwisecoolergarage/utilityroom

Somedehumidificationaswell

Recommendutilityroominstall.Why?- Extraheatinthatspace(Dryer/washer)- Isolatedoftenfromrestofhome

Importanttolocateaway fromthermostat


HPWHAirDucting/NoiseIssue

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Mostmanufacturerson3or4th generationOfHPWH.Muchmorequiet

ForinstanceRheem unitclaimsOnly49dBforlatestunit

Othersnowmuchmorequiet


AirflowConfiguration

EastFRTFBuildingMeasured

Airflow (cfm)

WestFRTFBuildingMeasured

Airflow (cfm)

BuildingPressureImpactDuringHPWHOperation

GaragetoGarage(7’) 160 160 NoneIndoortoIndoor(16’) 160 157 NeutralOutdoortoIndoor(19’) 147 148 Positive

TestedAirflowPathways


Site

#ofOccupants Config.

HPWHEnergyPost(kWh/day)

CoolingEnergyPre(kWh/day)

CoolingEnergyPost(kWh/day)

CoolingSavings(kWh/day)

CoolingSavings(%)

ACSEER

1 4 Interior 2.1 16.3 14.5 1.8 10.8 13.05 2 Ducted 2.7 44.7 43.0 1.7 3.8 13.09 2 Ducted 3.2 11.5 10.0 1.5 13.2 <1313 2 Interior 2.6 6.8 6.1 0.7 10.7 15.526 5 Ducted 3.5 11.5 10.1 1.4 12.3 17.050 4 Ducted 2.7 18.5 17.8 0.7 3.9 17.051 2 Ducted 1.3 15.0 14.2 0.8 5.6 16.056 3 Interior 3.1 18.9 18.7 0.2 2.7 10.0

Avg. 3 N/A 2.6 17.9 16.8 1.1 7.9Med. 2.5 N/A 2.7 15.6 14.3 1.1 8.2

SpaceCoolingEnergySavings(~1yearpreand1yearpost)


NewTech:PV-AssistedHPWH80%+Energysavingsvs.Electricresistance

- Nomoredailyenergyusethanarefrigerator

LargereductionstoGreenHouseGasEmissionsrelativetoelectricorgaswaterheaters


FSEC’sPV-HPWH:Prototype• UseCurrentGenerationHPWH 80%+

energysavings• Dedicated620WPV&micro-Inverters• Mixing/Anti-scaldvalve:set@125⁰C• SmartControls&programmedforadded

thermalstorage– -Normalthermostatset:125F

-Whensolaravailability=High,Auto-setthermostatto160⁰F

-OverallCOP=5.4(Florida)• Competitive;partscost($2000)retail• Conventionalsolarwaterheatersoften

>$7000- $10,000installed

310WPV+

310WPV

300-wattMicroinverters

60galHPWH


PV-HPWHPerformanceExample


PV-DrivenHPWHvsStandardElectric50gallonWaterHeater

Average=7.18kWh/dayHotWater@125⁰F =54.4gpd

Average=1.23kWh/dayHotwater@125⁰F=57gpd


AdvantagesofPV-HPWH• Superiorperformancetosolarthermal• Nonet-meteringagreement• Muchlowercostthan(perhapshalfsolarthermal)• Simple&fastinstall:Noplumbing,light-weightmodules• Betterwinterperformance:nofreezeprotection

– PVoutputhigherinwinter,nopipinglosses• Solidstate=Morereliable/longerlife

– lowermaintenancethansolarthermal• Stores2.3kWhthermal/dayaboveset@nocost• Produceshotwatereveninapoweroutage• Betterfutureperformanceavailable

– HPWHCOPsnow3 – 3.5vs.prototypecompressor(2.2)– PVmoduleefficienciesincreasing=smallermodulefootprint

• Seasonaltilttrackingpossiblegivensmallsize

• Disadvantage:notyetmanufactured


SpreadsheettoEstimateAllThisforYouOnlyafewinputs:fairlysophisticatedestimationofwaterdemand;sizeofhouseholdandagesYes,researchshowsteenagersuse3xasmuchhotwater


ALittleSummary• HPWHinstall:Building

locationimportant– Garagemayreducewinter

efficiency– Locateawayfromthermostat

• Interiorlocationcanprovidehelpfulsummercooling

• Whenductingair,knowwhereairiscomingfrom

• Compressoroperationlimitedw/ambienttempsbelow40⁰F.NotbiglimitationinCA

• HPWHisidealformildU.S.climates

• LargeGHGreductions• HPWHbesttechnologyfor

waterheatinginanallelectrichome

• FuturePV-HPWHtechnologypromiseslesswaterheatingenergythanarefrigerator

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Heat Pump Water Heaters: A Key Energy Technology for ...€¦ · Heat Pump Water Heaters: A Key Energy Technology for California Passive House California April 2018 Danny S. Parker

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