Troubleshooting Modern

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Troubleshooting Modern All Climate Air-to-Air
Heat Pumps Friday, September 14th, 2007 10 a.m.
12 Noon Presenter-Greg Jourdan, CM At the 70th
RSES Conference San Antonio, Texas
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Troubleshooting Modern All Climate Air-to-Air
Heat Pumps (ACHP)Agenda

• Sequence of Operation
• Traditional vs. All Climate Heat Pumps
• Typical Problems with Heat Pumps
• Thermostats
• Troubleshooting the Indoor Units
• Troubleshooting the Outdoor Units
• Checking the Charge
• Schematics
• IR Temperatures Principles
• Case Study Examples of ACHP Performance

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Heat Pump Quiz-True or False

• True or False Heat Pumps are really just
  reversible air conditioners,
• they cool in the summer and heat in the
  winter.
• True or False Heat Pumps dont work very well
  below 30ºF or in
• colder conditions without some form of
  auxiliary heat.
• True or False Heat Pump technology has evolved
  where several
• manufacturers design operation down to 5-10
  ºF and
• one heat pump which operates down to -15
• ºF ambient conditions without auxiliary
  heat.
• True or False All Heat Pumps work the same way,
  some just cost
• more.
• 5. True or False The first thing to troubleshoot
  on a heat pump is the
• refrigerant charge.

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Heat Pump Quiz-True or False

• True or False Micron gauges arent needed in the
  real world,
• because your gauges tell you when you have
  reached a deep vacuum down at 29.92 inches.
• True or False It isnt really necessary to check
  fan or compressor amps, because it isnt
  much help.
• True or False Suction line temperatures on a hot
  summer day should be as cold as a beer can
  or about 35f.
• True or False Modern heat pumps are using Direct
  Current ECM motors to control fan speed
  automatically.
• True or False Heat Pump Thermostats are
  different than standard thermostats and
  must be selected for the application.

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Heat Pump Quiz-Answers

• True or False Heat Pumps are really just
  reversible air conditioners,
• they cool in the summer and heat in the
  winter.
• True or False Heat Pumps dont work very well
  below 30ºF or in
• colder conditions without some form of
  auxiliary heat.
• True or False Heat Pump technology has evolved
  where several
• manufacturers design operation down to 5-10
  ºF and
• one heat pump which operates down to -15
• ºF ambient conditions without auxiliary
  heat.
• True or False All Heat Pumps work the same way,
  some just cost
• more.
• 5. True or False The first thing to troubleshoot
  on a heat pump is the
• refrigerant charge.

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Heat Pump Quiz-Answers

• True or False Micron gauges arent needed in the
  real world,
• because your gauges tell you when you have
  reached a deep vacuum down at 29.92 inches.
• True or False It isnt really necessary to check
  fan or compressor amps, because it isnt
  much help.
• True or False Suction line temperatures on a hot
  summer day should be as cold as a beer can
  or about 35f.
• True or False Modern heat pumps are using Direct
  Current ECM motors to control fan speed
  automatically.
• True or False Heat Pump Thermostats are
  different than standard thermostats and
  must be selected for the application.

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Heat Pump SystemSequence of OperationTraditional
Unit
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Heat Pump SystemOperation-Traditional Unit
Low Pressure Vapor
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Heat Pump SystemEfficiency-Traditional Unit
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Heat Pump SystemIllustration-ACHP Unit

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Heat Pump SystemPh Chart Illustration-ACHP Unit

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ACHP System Cooling Modes

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Performance Studies of Split System Heat Pumps

• Airflow too low in 70 of systems
• Refrigerant charge incorrect in 74 of units

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• Four Primary HVAC Installation Related Energy
  Problems
• Duct Leakage
• Refrigerant Charge
• System Airflow
• Sizing

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Duct Leakage to Outdoors
CFM 50 leakage

Mean 395
Percent of Homes
N78
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Audit Duct Leakage to Outdoors Before duct
repairs
CFM 50 leakage

Median428
Percent of Homes
N116
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Audit Duct Leakage to Outdoors After duct
repairs
CFM 50 leakage

Median184
Percent of Homes
N117
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Heat Pump System Indoor AHU Troubleshooting-Duct
System

• Check for Adequate Supply and Return Ducts
• Check for Restrictions, i.e.. Furniture, closed
  vents, dirty filters, etc.
• Check for Air LeaksLook for Sealed DuctsDont
  use DUCT TAPE..It does not sealUse a duct seal
  paste or caulk.
• Check for Proper Size Ducts
• Avoid Flex Ducts as Much As Possible

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Primary Heat Pump Components to Check When
Troubleshooting

• Thermostat
• Indoor AHU
• Outdoor Unit
• Electrical
• Refrigerant Charge
• Air Flow

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The Thermostats are Universal and Need to be
Properly Programmed

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Thermostat Programming

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Troubleshooting the ThermostatLearn to Read the
Manufacturers Instructions (RTMI)Sample

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Indoor ThermostatIs it Mounted in the Proper
Location?

• Inside Wall
• Locate in the Return Air
• Mount at approx. 5
• Free of Drafts
• Not Next to Computers or Heat Source
• No Direct Light on T-Stat

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Troubleshooting theIndoor AHU-Standard Product
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Heat Pump System Indoor AHU Troubleshooting

• Always start with manufacturers literatureKnow
  the designed sequence of operation. Dont ASSUME
  anything.
• Confirm thermostat is programmed and wired
  correctly.
• Check settings on jumper pins and dip switches
• Check for proper high voltage
• Check low voltage control signal
• Inspect for loose plugs or connections
• Confirm that no safeties or lockouts are
  preventing operation.
• If fan motor not running, do not assume ECM motor
  failure.
• Check thermostat signal, then controller on AHU,
  then motor controller, and then the motor power.

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Indoor Unit Circuit Board
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Indoor Unit Circuit Board
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Understand the Status and Fault CodesThe control
board includes an LED that displays status and
fault codes. The control will display the fault
codes until power is removed from the control or
the fault condition is no longer present.

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Be Sure of AIRFLOW SELECTIONThe airflow and
comfort setting selection jumpers must be set
properly at the time of installation for proper
system operation. NOTE Incorrect airflow and
comfort settings may result in decreased system
efficiency and performance.

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Nominal Air Flow Chart Leaving Air Temp.

• Find evaporator entering air dry bulb temperature
• Find evaporator entering air wet bulb temperature
• Provides evaporator leaving air dry bulb
  temperature
• If not within /- 3 F, adjust fan speed

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ECM Motor Principles

• The motor is essentially a three phase motor with
  a permanent magnet rotor. The permanent magnet
  rotor contributes to the electrical efficiency of
  the ECM and also to its sensor-less ability to
  control the rpm (revolutions per minute) and
  commutation (when to alternate the cycle).
  Typical DC motors require brushes to provide the
  commutation function. This is where the motor
  gets the name brushless DC motor.
• The benefit of all of this technology is
  increased electrical efficiency and the ability
  to program more precise operation of the motor,
  over a wide range of HVAC system performance
  needs, to enhance consumer comfort.

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CFM and ESP AHU Fan Operation

• These variable speed air handlers are designed to
  deliver constant airflow (CFM) regardless of the
  external static pressure (ESP) in the ductwork.
• If too many supply registers are closed, a filter
  becomes clogged, or there is a restriction in the
  ductwork, the motor will automatically operate at
  a higher speed to compensate for the higher ESP.
  This may result in a higher operating sound
  level.
• All airflow (CFMs) are shown at 0.5 w.c.
  external static pressure.
• These units have variable speed motors that
  automatically adjust to provide constant CFM from
  0.0 to 0.6 w.c. static pressure. From 0.6 to
  1.0 static pressure, CFM is reduced by 2 per
  0.1 increase in static.
• Operation on duct systems with greater than 1.0
  w.c. external static pressure is not recommended.

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PSC vs. ECM Motors
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ECM Motors
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The Motor Control

• The motor control is the brains of the device,
  where single phase (1Ø) 120 or 240 VAC 60 cycle
  (Hertz/frequency) power is connected. The control
  then converts AC power to DC power to operate the
  internal electronics, thus the name DC motor.
• The microprocessor in the motor control is
  programmed to then convert DC power (by means of
  electronic controls) to a three phase (3Ø) signal
  to drive the motor, thus the name Three Phase
  Motor. It also has the added ability to control
  the frequency (which controls the speed in
  revolutions per minute) and the amount of torque
  (current/power) it delivers to the motor.

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Testing Motor Windings

• Check the resistance of the motor windings to
  determine if a fault has occurred.
• On single phase motors measure start to common
  winding, run to common winding, and start to run
  winding.
• On 3 phase motors, check phase to phase and phase
  to ground.
• Ohms reading between phases should be equal
• No continuity from any phase to ground

Typical resistance test on a 1? motor
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Testing Motor Capacitor Measurements (when on the
unit)

• To test a capacitor
• Remove capacitor from the circuit
• Discharge capacitor via the bleed resistor or
  with a 20 k? 2 W resistor
• Measure capacitance with the appropriate meter.
  Your results should be within the "mfd" range of
  the capacitor specifications
• If the capacitor is faulty, replace it with an
  exact match
• Shorted capacitors may lead to premature failure
  of the motor.
• Open capacitors or capacitors that have changed
  in value may result in poor starting.

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The Outdoor Equipment-ACHP Unit
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CONTROL ERROR CODESOn Outdoor Units

• In the event of a failure in the outdoor unit,
  the control has a built in diagnostic LED for
  troubleshooting purposes. Figure below shows the
  location of the diagnostic LED on the ACHP
  control board. During normal operation this LED
  fades on, and blinks off continuously. If for any
  reason the unit has encountered an error
  condition, the error may be diagnosed using the
  error table below.

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Troubleshooting the Outdoor Unit

• Know What is the Sequence of Operation
• Remember to always test for Proper Volts and Run
  Load Amps

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The Outdoor Compressors-ACHP Unit
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Outdoor Unit Circuit Board

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Outdoor Unit Circuit Board
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Line Voltage Components
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Checking the ChargeSuperheat Definition
Superheat is the additional temperature increase
beyond the evaporation point of the refrigerant
in the evaporator. (Liquid will destroy the
compressor.) Superheat is measured in three
steps 1. Measure the suction (inlet) pressure to
the compressor. Using a Pressure/temperature
(P/T) chart, find thecorresponding evaporation
temperature (Tvapor). 2. Use a thermometer with
a probe to measure the actual suction line
temperature (Tmeasured). 3. Superheat
(Tmeasured) - (Tvapor).

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Superheat Why Measure?

• Suction line superheat is a good place to start
  system diagnosis.
• Incorrect superheat values can indicate various
  system problems such as a clogged filter drier,
  refrigerant undercharge / overcharge, faulty
  metering device, or improper air flow.

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Subcooling Definition

• Subcooling is the additional temperature below
  the condensing point of the refrigerant in the
  condenser.
• Subcooling assures that the refrigerant does not
  begin to boil (change phase) until it has passed
  through the metering device.
• Subcooling is measured in three steps
• Measure the liquid pressure at the exit of the
  condenser. Find the corresponding condensing
  temperature (Tliquid).
• Use a thermometer to measure the actual liquid
  line temperature (Tmeasured).
• Subcooling (Tliquid) - (Tmeasured).

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Subcooling Troubleshooting

• An incorrect subcooling value can indicate
  various system problems, including insufficient
  airflow across the condenser, refrigerant
  undercharge/overcharge, or a faulty metering
  device.
• Subcooling expected values can range greatly
  depending upon the design and purpose of the
  system.
• Subcooling along with subcooling is often the
  most popular method to charge modern heat pumps
  because of the TXV metering devices for increased
  efficiencies.

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Subcooling Expansion Valves

• Subcooling is the preferred method for
  Fine-Tuning the refrigerant charge for systems
  utilizing a Thermal Expansion Valve (TXV or TEV).
• An expansion valve modulates to control superheat
  at the evaporator at a pre-determined value
• Adding or recovering small amounts of refrigerant
  charge may not result in a change in superheat,
  but will result in a change in subcooling.
• Older low SEER equipment generally has more
  subcooling.
• Newer high SEER equipment generally has less
  subcooling.
• Always follow manufacturers subcooling charging
  guidelines.

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Checking the Temperature SensorsBe Sure to Use a
Good DDM

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Sub-Cooling for Heating Mode to Establish Charge

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Adding to Refrigerant Charge to Compensate for
Refrigerant Line Length

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Basics of Electrical Troubleshooting the Heat Pump

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Line Voltage Schematic
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Outdoor Unit Control Board Interface

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Learn to Use IR Test Tools forInfrared
Thermometry Applications

• IR temperature measurement isideal for
  applications involving
• hot surfaces
• rotating objects
• electrically live surfaces
• difficult-to-reach locations
• speed and relativity of temperature

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Infrared Temperature Measurement

• Infrared is low-level light energy, not visible
  to the human eye.
• All objects naturally emit infrared energy.
• IR thermometers use special optics to measure
  this invisible energy.

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Infrared Thermometry Applications

• IR temperature measurement isideal for
  applications involving
• Hot surfaces
• Rotating objects
• Electrically live surfaces
• Difficult-to-reach locations
• Speed and relativity of temperature

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Infrared Temperature Measurement

• Optical resolution
• Ratio of the distance from the measured object
  vs. the sampling spot size.
• Examples
• 41 optical resolution 4 away from
  measuredobject ? 1 diameter sampling size
• 101 optical resolution 20 away from
  measuredobject ? 2 diameter sampling size
• Know your application! An IR device with a 41
  optical resolution can not effectively be used to
  measure a diffuser temperature 15 away.

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Field of View with IR Temperature

• Field of View refers to the target size relative
  to the IR thermometers spot size.
• Ideally, the target surface to be measured should
  be twice the size of the spot.
• If the spot size is larger than the surface to be
  measured, measurement errors are increased.

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Infrared Temperature Measurement

• Emissivity is a numerical value between 0 and 1
  which indicates the ability of an object to emit
  infrared energy.
• Emissivity is determined primarily by the
  material from which an object is constructed
  and its surface finish.
• Examples
• Polished brass 0.03
• Roughly polished copper 0.07
• Oxidized brass 0.61
• Black oxidized copper 0.78
• Black lacquer paint 0.96

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Infrared Temperature Measurement

• Emissivity
• Low cost infrared measurement instruments are
  typically fixed at a 0.95 emissivity.
• To get an accurate temperature reading, the
  surface being measured must be close to 0.95
  emissivity.
• A shiny surface can be covered with black
  paint, electrical tape, magic marker, or any
  other item which will be less reflective.

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WVC College Outdoor Units
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WVC College Indoor Lab Units
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The Outdoor Equipment-Nyle Unit
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The Outdoor Equipment-ACHP Unit
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The Indoor Equipment-ACHP Unit
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Indoor-Outdoor Data Loggers
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Review of WVC ACHP Recorded Performance Data from
local Electric Utility

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Review of WVC ACHP Recorded Performance Data from
local Electric Utility

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Review of WVC ACHP Recorded Performance Data from
local Electric Utility
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Challenges and Obstacles for HVACR Service
Contractors

• HVAC/R Systems are becoming more complex.
• Micro-processors and solid state training needs
  to be part of the HVAC curriculum.
• Future trends and demands for skilled labor is
  creating shortages (not enough people entering
  blue collar trades)
• Equipment costs are rising due to metal shortages
  worldwide

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Review of Heat Pump Troubleshooting Guidelines

• Read Mfg Installation Instruction
• Be sure of proper size duct system
• Seal ducts with proper product (do not use old
  fashion duct tape, it does not seal)
• Pull deep vacuum prior to charging
• Check Thermostat for Proper Operation
• Check for proper charge upon startup and
  troubleshooting, but only when necessary.
• Verify all electrical connections and piping for
  insulation and tightness
• Use the Right Tools and Be Safe

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Any Questions on Troubleshooting Heat Pumps?

Thank You Greg Jourdan Wenatchee Valley College