Heat Pump Research Project

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Heat Pump Research Project
Sponsored by the Heat Pump Working Group June 7,
2005
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Project Goals

• Assess energy use and savings from heat pumps
  installed under CRD/ConAug and EWEB.
• Assess base case installation practices.
• Assess heat pump performance under laboratory
  conditions to identify optimal settings.
• Assess the general approach of installers to
  control, sizing and performance issues, and of
  manufacturers to new technologies, etc.

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Billing Results
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EWEB Billing Analysis Results
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CRD / ConAug Billing Analysis Results
Revised Results
Previous Results
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Billing Analysis Results by System Type
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Billing Analysis Results by Building Type
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Billing Analysis Results by Vintage
Legend 1 Pre 1981 2 1981 1994 3 Post 94

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Realization Rates by Program Year Base
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Realization Rates for CRD Calculator, Initial
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Realization Rates, Revised
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kWh Savings estimates
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Laboratory Results
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HSPF Fixed Orifice TXV
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Summary of Lab Results

• Impacts of refrigerant charge minimal except at
  very reduced levels (70 of specification)
• Impacts of air flow also limited to cases with
  very low air handler flow (less than 300
  CFM/ton).
• Low air flow appears to occur in about 25 of
  base case installation practice
• TXV improves overall performance but has minimal
  impacts on the effects of low charge and low air
  flow
• Cd higher than modeling assumptions for fixed
  orifice, lower than assumption for TXV
• Defrost degradation factors largely stable at
  values near the modeled and manufacturers
  assumptions.

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Field Data Summary
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Field Study Overview

• 160 field sites in 4 regions (Central Oregon,
  Kitsap Peninsula, Clark Co., Yakima/Walla Walla)
  started September 2004
• Base case sites, chosen at random to represent
  non-PTCS installations
• Combine field findings with billing data to
  recalibrate performance assumptions used in RTF
  calculations
• On-site review consists of two visits
• Duct/house review (complete)
• Heat pump review by service tech. (110 sites now
  in, additional 15 sites expected)

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Site Selection

• Sites selected via random telephone dial to have
  air-source heat pump and be within appropriate
  utility territory
• Sites might have basements/interior ducts
• Clark County chosen vs. Portland because of
  paucity of HPs in PDX Pacific Power svc territory
• Clark actually has HP inspection program so
  non-typical vs other areas

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Key Audit Outputs(house/duct)

• House heat loss rate (UA)
• Integral part of modeling house performance vs
  bills
• Includes infiltration component (blower door
  test)
• System airflow (CFM)
• System capacity efficiency
• Duct system insulation and leakage
• System operating pressures also measured
• Duct leakage fraction ()
• Effect on overall delivery efficiency/energy use
• Homeowner interaction with system (via survey)

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Key Audit Outputs (heat pump review)

• HP control strategy
• Indoor thermostat type, setting and staging
• Outdoor thermostat presence, setting and
  operation
• Compressor low ambient cut out
• Refrigerant charge level

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Building Characteristics Heat Loss Rate
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Blower Door Results

• Median ACH50 is 7.6 for 149 clean cases mean is
  8.3
• This converts to median ACHnat of 0.38
• Highest ACH50 19.0
• Lowest ACH50 1.6

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Blower Door Results by Vintage Bin
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Duct Leakage Fraction (all sites)
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Duct Leakage by Vintage Bin
Supply Side
Return Side
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Supply vs. Return Leakage
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System Fan Flow

• Median flow is 340 CFM/ton (n126)
• Lower quartile is lt292 CFM/ton
• ECM cases (n21), median flow is 338 CFM/ton
• final will be larger

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Airflow Distribution
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System airflow by size of outdoor unit
Tons
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Refrigerant Charge Evaluation

• Review predominantly done in swing seasons
• Heating season evaluation combined techs review
  of operating pressures and sensible split in
  context of ambient temp., system airflow, coil
  match
• About 1/3 of systems evaluated in cooling only
  mode or in addition to heating mode
• Superheat/subcooling evaluation

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Charge Results

• 60 of cases evaluated as having correct charge
• 28 of cases evaluated as being overcharged
• 10 of cases evaluated as being undercharged
• 2 had serious leaks (no refrigerant)

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Refrigerant Charge Digest

• Over/undercharge amounts likely under-reported vs
  weigh-in approach
• However, cases of severe undercharge were very
  limited
• ½ of overcharged cases had an accumulator
• 2/3 of remaining overcharged cases were units
  with Trane compressors or scroll compressors

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Heat Pump Efficiency
HSPF by Region
HSPF by Equipment Size
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HVAC Usage(from median low bill analysis of 124
bills)
Heating - Annual kWh
Cooling - Annual kWh
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Normalized Heating Load by Vintage and Region
Heating - Annual kWh/sf
Total Usage - Annual kWh/sf
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Normalized Heating Usage
Impact of wood Annual kWh/sf
Percentage of Sample Using Wood
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Modeled Duct Efficiency(efficiency of 1 is
perfect ducts)
By Region
By Vintage
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Duct Insulation
Supply vs. Return UA
R-Value of Supply Ducts
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TXV Summary (Outdoor Unit)
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TXV Summary (Indoor Unit)
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Thermostat/Homeowner Interaction

• 80 of systems have programmable stats
• 1/3 of occupants say they understand their
  thermostat and/or like how it keeps their house
  comfortable
• 1/3 say they tolerate their thermostat (but wish
  they understood it better)
• 1/3 have thrown up their hands and use the HOLD
  feature

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Controls Indoor Thermostat

• 78 programmable
• Median heating setpoint 70? F
• Median setback 65? F
• 55 of systems with setback gt 5? F
• Estimated 75 of programmable stats have adaptive
  recovery

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Controls Outdoor Thermostat

• About 35 of sites visited had an operating ODT
  (75 of Clark sites have ODT)
• Average setting 40 F
• About 2/3 of sites without ODTs had the extra
  wires needed to install one without fishing new
  wire
• Only 15 of systems had elements on in Stage 1
  heating
• Median on-time 5 minutes

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Market Actor Interviews
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HVAC Installer Interviews(detailed results)

• 32 shops throughout region in urban, suburban,
  rural areas (29 full interviews)
• Shops range from 2 trucks to 30, median of 6
• Median 50 new construction
• Participants install all major (and some
  secondary) brands of equipment
• Almost all participants report use of
  non-intuitive heat pump and duct sizing tools
  (Manual J, Manual D, etc.)
• Wide range of experience with utility, state,
  national incentive/marketing campaigns and
  installation procedures

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Technician Certification
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Installer System Sizing Criteria
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Characteristics of Efficient Line
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Installation Characteristics - TXVs
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Availability/cost of Outdoor Unit TXV
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Acceptance of TXV Technology
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Outdoor Thermostat/Low Ambient Cutout
All often cases in TriCities/Yakima All
seldom cases as above or Mid-Columbia
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Installation Characteristics Aux Heat
Out of 7 cases answering seldom or often, 5
In Zone 2 (E Wash or Boise)
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Installer Target System Airflow
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R410a
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PTCS
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Familiarity With Third Party Charge Checking
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Acceptance of Third Party Mechanisms
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Energy Star
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Penetration of Incentives Tax Credits
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Marketing Impacts
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Challenges in Explaining Tax Credits/Incentives
to Customers
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Client Priorities
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Comments on Thermostats
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Perceived Trends