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Air Conditioner & Heat Pump Efficiency Ratings: this article explains air conditioning SEER energy efficiency ratings for air conditioners and heat pumps along with related terms like BTUs, Watts and hourly operating cost, in easy to understand language. Latent heat, superheat, latent heat of vaporization, latent heat of condensation, sensible heat & specific heat and joules are defined here.

Also see AIR CONDITIONING HEAT PUMP SAVINGS for suggestions on cutting A/C or heat pump operating cost. For a history of the US Government's use of energy efficiency ratings for air conditioners, also see SEER RATING HISTORY. More definitions of electrical terms can be found at DEFINITIONS of ELECTRICAL TERMS and other heating and cooling terms are at DEFINITION of Heating & Cooling Terms. This website answers most questions about air conditioning systems. We continue to add to and update this text as new details are provided. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

© Copyright 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.

SEER RATINGS EXPLAINED - determining Seasonal Energy Efficiency of Air Conditioning Systems

SEER stands for "Seasonal Energy Efficiency Ratio. This is a measure of the energy efficiency of the air conditioning system. SEER ratings permit consumers to compare operating costs of various cooling systems and products.

SEER = [Total Cooling Output Over the Cooling Season] / [Total Electrical Energy Input Over the Cooling Season]

Higher air conditioning SEER rating means more efficient, or in other words lower energy cost to cool the building. Older air conditioning systems are likely to have a lower SEER (perhaps 5 or 6) than a newer more efficient system (perhaps SEER=10). But beyond comparing SEER ratings, a look at the building insulation, air leakage, and the layout, insulation, and adequacy of the air conditioning duct system are likely to have a very large, usually determining effect, on the operating cost of air conditioning systems in buildings.

Here are the U.S. Government's Energy Star Program definitions of SEER and EER: [1]

Seasonal Energy Efficiency Ratio (SEER): This is a measure of equipment energy efficiency over the cooling season. It represents the total cooling of a central air conditioner or heat pump (in Btu) during the normal cooling season as compared to the total electric energy input (in watt-hours) consumed during the same period. SEER is based on tests performed in accordance with ARI 210/240.48

Energy Efficiency Ratio (EER): This is a measure of the instantaneous energy efficiency of cooling equipment. EER is the steady-state rate of heat energy removal (e.g., cooling capacity) by the equipment in Btuh divided by the steady-state rate of energy input to the equipment in Watts. This ratio is expressed in Btuh per Watt (Btuh/Watt). EER is based on tests performed in accordance with ARI 210/240.

At Questions & Answers about the Energy Star Program's SEER and EER definitions and equipment ratings you'll see discussion about some confusion around just what the SEER rating means for individual air conditioner components versus the SEER or EER for the whole A/C system.

The Energy Star program also provides a performance rating factor for heat pumps since those units, unlike straight air conditioning systems, operate through both heating and cooling seasons:

Heating Seasonal Performance Factor (HSPF): This is a measure of a heat pump's energy efficiency over one heating season. It represents the total heating output of a heat pump (including supplementary electric heat) during the normal heating season (in Btu) as compared to the total electricity consumed (in watt-hours) during the same period. HSPF is based on tests performed in accordance with ARI 210/2401.

We note that because electrical energy costs vary widely in different areas of North America, and because in some areas the electric utility may give preferential rates (reduced rates) for people using electric heat, the HSPF number may need adjustment for your area.

Also see ENERGY STAR PROGRAM and for tips on how to cut air conditioning or heat pump operating costs, see AIR CONDITIONING HEAT PUMP SAVINGS.

How Much Energy Does an Air Conditioning System Use?

How to Calculate Energy Usage using an Air Conditioner's SEER rating

A concise way to translate SEER number directly into energy cost is SEER 10 = 10 BTUs/WattHour. In other words, an air conditioner that has a SEER rating of 10 will provide 10 BTUs of cooling per WattHour (Wh) of operation.

So if our air conditioner has a SEER of 9, it is less efficient than an A/C unit with a SEER of 10 because our SEER 9 air conditioner produces 9 BTUs of cooling for the same Wh of operation. That is, we've kept the energy consumption (one Wh) the same, but we got less cooling output.

Let's define Watts and BTUs so we can better understand these air conditioner figures of SEER efficiency, BTUs, Watts, and air conditioning operating cost calculations.

What is the SEER for Older Air Conditioners?

Older air conditioning systems are likely to have a lower SEER (perhaps 5 or 6) than a newer more efficient system (perhaps SEER=10). But beyond comparing SEER ratings, a look at the building insulation, air leakage, and the layout, insulation, and adequacy of the air conditioning duct system are likely to have a very large, usually determining effect, on the operating cost of air conditioning systems in buildings.

Testing Requirements for SEER Ratings for Air Conditioners & Heat Pumps

According to the ENERGY STAR program requirements,

Testing Requirements: Manufacturers are required to perform tests and self-certify those product models that meet the ENERGY STAR guidelines. Partner agrees to perform energy-efficiency tests for residential ASHPs, central air conditioners, and gas/electric package units under rating conditions in accordance with ARI 210/240. For EER, manufacturers agree to perform energy-efficiency test based on ARI Standard 210/240-94, Operating Condition A: 95°F outdoor air temperature, 80°F dry bulb/67°F wet bulb indoor coil air entering conditions. The HSPF and SEER ratings shall be identical to the levels reported on the Federal Trade Commission (FTC) Energy guide Label.

It is EPA’s intention to utilize the CEE Directory of ARI Verified Equipment to determine which equipment qualifies for ENERGY STAR. Any manufacturers that do not participate in the ARI certification program will be expected to submit product information directly to EPA for listing on the www.energystar.gov web site.[1]

Air Condition, Refrigeration, & Heating System Standard Definitions

What is a Watt Hour or Wh?

What's a WattHour? Watt hours (Wh), sometimes written W.h, can measure either electrical energy produced, say by a power station, or Watts can measure the amount of electrical energy consumed (say at a light bulb or an air conditioner in our home). For air conditioners, the A/C units' total Wh is the energy used in running the air conditioning system for an hour.

see DEFINITIONS of ELECTRICAL TERMS for details about volts, watts, amps, and power factor.

How do we calculate watts, volts, and amperage for an electrical device like an air conditioner?

Watts (W) as used in a simplified manner here and by electricians, is a measure of electrical power and is expressed by any of the formulas shown below. [All forms of power are measured in units of Watts, W, but this unit is generally reserved for real power (see definitions further below.]

DC circuits: W = V x I (this is a simplified formula and is technically exactly correct for DC circuits. For AC circuits,

• V*I=VA  not watts.   In an AC circuit, things are more complicated. An electrical load in an AC circuit will typically use both real power - P - and reactive power - Q - (definitions below).

AC circuits: Watts   W=V*I*PF  where PF = power factor

see DEFINITIONS of ELECTRICAL TERMS for details about volts, watts, amps, and power factor. Also see AMPS & VOLTS DETERMINATION "How to estimate the electrical service ampacity and voltage entering a building".

Reader Daniel Mann adds that "Watts is correctly shown as Watts-Voltage times Current times power factor.  Since power factor varies all over the place,..." [W = V x I] "perpetuates misinformation". We include additional more technical explanation of power factor, real power, apparent power, complex power, and reactive power as we elaborate at DEFINITIONS of ELECTRICAL TERMS.

Lots of electrical appliances include a label providing the appliance's wattage, and in the case of heating and air conditioning equipment, lots of other details are provided too. see A/C DATA TAGS for details.

What is a BTU or British Thermal Unit? What is a Joule?

Definition of BTU - British Thermal Unit

A BTU is a measure of heat energy. One BTU is the amount of heat energy we need to raise the temperature of one pound of water by one degree Fahrenheit. One BTU also is defined as 252 heat calories (this is not the same as food calories). When talking about air conditioners or heaters, we talk about the A/C unit's BTUh capacity - the number of BTUs of cooling (lowering rather than raising temperature) it can produce in an hour of running.

Also see DEFINITION of Heating & Cooling Terms where we further discuss and define BTUs, Calories, and other energy measures.

Here is a table of BTUs translated into other measurements:

Notes to the BTU table:

(1) How many BTUs are required to convert one pound of water at 212 degF to one pound of steam vapor at 212 degF? This figure is the latent heat of vaporization, the number of BTUs of energy used to raise one pound of water at 212 degF to one pound of steam vapor at the same temperature; in other words, the temperature is unchanged but the state of matter is changed from liquid to vapor. - Refrigeration License Examinations. Also see BLEVE explosions or boiling liquid vapor expansion explosions. We discuss the role of pressure/temperature relief valves in protecting against these hazards at RELIEF VALVES - TP Valves on Boilers and at RELIEF VALVES - Water Heaters.

Other definitions related to BTUs and heating or air conditioning: Latent heat, super heat, latent heat of vaporization, latent heat of condensation, sensible heat & specific heat are defined here

Latent heat is defined as the amount of heat absorbed by a substance with no change in a temperature - such as when a substance changes state (from water to steam, for example)

In other words, heat that is absorbed by a substance with no change in temperature is latent heat. For example when a substance changes state (liquid to gas) latent heat is involved.

Definition of Superheat: The latent heat of vaporization is defined as the number of BTUs to raise one pound of liquid to a pound of vapor (to a varying degree per BTU depending on the type of vapor - this is "superheat"). Our Sketch explaining latent heat of vaporization shown at left is provided courtesy of Carson Dunlop.

The latent heat of condensation is defined as the number of BTUs necessary to change a state back from a vapor to a liquid

The latent heat of solidification is defined as the amount of energy (or number of BTUs) needed to change a liquid to a solid (such as water to ice) while the temperature remains unchanged (at sea level, 32 degF).

Sensible heat is defined as the amount of heat that we can sense or feel or measure.

When an air conditioner system is working, the larger diameter tubing on the low-side of the system combined with the effects of the refrigerant metering device (cap tube or thermostatic expansion valve) results in a reduced pressure on the low side (compared with high side pressure). The reduced pressure causes vaporization of the liquid refrigerant inside the cooling coil, which in turn means that sensible heat is absorbed by the cooling coil.

When the same air conditioner system is working, the smaller diameter tubing on the high side reduces available volume so that (along with the effect of the compressor itself) we increase the pressure and temperature of the refrigerant so that sensible heat can be transferred to ambient outdoor air.

Specific heat is defined as the amount of heat required to raise the temperature of a given substance by one unit of temperature (in our examples by one degF.) Specific heat is also defined as the amount of heat (in calories) to increase the temperature of one gram of a substance by one deg C (Celsius).

The specific heat of water is defined as a constant and = 1
The specific heat of ice is is 5

• Definition of one BTU is the energy required to raise one pound of water by one degree F (sensible heat).

In which direction does heat flow: heat energy always flows from the warmer substance to the cooler substance, down to -460 degF where all molecular movement stops.

A neat fact is that the heat flows more rapidly (efficiently) between two substances when there is a greater temperature difference between them. That's why the thermal conductivity of finned copper tubing heating baseboard is exponentially greater at higher degrees of heating water temperature, and that's why we like to run our heating boiler at a higher rather than a lower upper limit temperature.

Also see DEFINITION of Heating & Cooling Terms

Definition of Joule

Note: Outside of the U.S. and some other places, BTUs is being replaced with the SI unit of energy, the Joule. (J). The English have beaten out the Scots by James Prescott Joule who defined this value. since there are 3600 seconds in an hour) the following formulas equating Watts, Joules, and Newton meters can be written:

1 Watt second (Ws) = 1 joule (J) = 1 newton meter 1 Watt hour (Wh) = 3600 Joules

1 kilowatt hour = 3.6 x 10⁶ Joules, since there are 1000 watts in a kilowatt.

We can think of an air conditioner's "efficiency" as expressed either in the total operating cost for a season of use, or you may prefer to just express the air conditioner's efficiency as its operating cost to run the system for one hour.

The equation shown at page top is designed to reduce all of the parameters describing air conditioning efficiency to a single efficiency number, SEER. SEER numbers are useful when we're comparing one air conditioner with another. But suppose we want to know the actual air conditioning cost per season, or air conditioning cost per operating hour to operate our air conditioner?

To translate our air conditioners SEER rating into actual air conditioning operating costs we need to know:

How do We Translate BTUs to Tons of Air Conditioning or Cooling Capacity?

One ton of air conditioning capacity produces the same cooling ability as melting one ton of ice in 24 hours. Sketch courtesy of Carson Dunlop

288,000 BTUs / 24 hours = 1 Ton of cooling

12,000 BTUs / hour = a 1-ton air conditioning system

Or if we know the total number of BTUs at which an air conditioning system is rated, since this number is usually given in BTUH or BTUs / hour, we just divide that number by 12,000 to get the number of tons of cooling capacity.

A 36,000 BTUh air conditioner is providing 36,000 / 12,000 or 3 Tons of cooling capability per hour.

If we know the number of tons of cooling capacity that an air conditioning system is rated for, we just multiply the number of air conditioning capacity in Tons by 12,000 to get the number of BTUs of cooling capacity of the system.

A 3-ton air conditioner is providing 3 x 12,0000 or 36,000 BTUs of cooling capability per hour.

To assist in choosing the right sized air conditioner, we provide a typical air conditioner chart at AIR CONDITIONER BTU CHART.

Don't buy an air conditioner that is too big: if you install a system that is too powerful (too many tons of cooling capacity) the building will be less comfortable than if you install a properly-sized air conditioner. Too many tons of air conditioning mean the system will shut off on short cycles and won't run long enough to reduce the indoor humidity to a comfortable level.

How Much Electricity Does An Air Conditioner Use Per Hour?

How much electricity our air conditioner uses per hour is easy to calculate. Let's assume that the data tag on our air conditioner says that the unit is a 5000 BTUh device with a SEER rating of 10. This means our A/C unit will produce 5000 BTUs of cooling in an hour of running. Since SEER=10 means that 10 BTUs used per Wh, then

5000 BTUh / 10 SEER = 500 Watts per hour that our A/C unit will use.

How Much Electricity Does An Air Conditioner Use in one Cooling Season?

A common example we use (because the math is easy) is to assume we have 125 days of cooling season during which we run the air conditioner for eight hours per day.

8 x 125 = 1000 hours of cooling operation over a season
500 Wh (watts used per hour) x 1000 (hours per season) = 500,000 Wh per season

So we are using 500,000 Watt Hours of energy (electricity) per cooling season. We divide this by 1000 to convert to Kilowatts since that's how our electrical bill will express our electricity usage.

500,000 Wh / 1000 = 500 kWh or kilowatt hours per season of use
That's how much electricity we're using over the cooling season.

What is the Definition of High Side and Low Side in Air Condition & Refrigeration Systems?

Definition of Low Side in an Air Conditioning System refers to the components on the low-temperature and low-pressure side of the compressor unit. In an air conditioner, the low side includes the suction or intake side of the compressor unit, suction piping connected to the evaporator coil, the evaporator or cooling coil, and the output-end of the metering device or TEV.

Definition of High Side in an Air Conditioning System refers to the components on the high-temperature (above ambient air temperature) and high pressure side of the compressor unit. In an air conditioner in cooling mode these include the output or high pressure side of the compressor unit, the high pressure gas refrigerant line connected to the condensing coil, the condensing coil itself, and the inlet side of the metering device located near the evaporator coil.

These parts are named and illustrated at AIR CONDITIONING & HEAT PUMP SYSTEMS and at COMPRESSOR PRESSURE READINGS we discuss air conditioner system high side and low side further.

At OPERATING COST we determine the actual dollar cost of running an air conditioner either by the hour of by the season of use. It's easy to get from that data to actual air conditioning operating costs in dollars.

Questions & Answers about the Energy Star Program's SEER and EER definitions and equipment ratings

Question: I purchased a 16 SEER system. The unit outside has an energy rating of 14 SEER. Did my contractor install the wrong unit?

I purchased a 16 SEER system. The unit outside has an energy rating of 14 SEER. The company tried to tell me that the coils add 2 SEER to the overall system. I think that they are lying, and that they installed the wrong unit. What is the correct answer? - Michelle

Reply: Maybe. Rely on the product labels and check with the manufacturer about the combined SEER of your compressor/condenser unit and air handler unit

Michelle, the US EPA / Energy Star program's definition of SEER given at the top of this page describes the "... total cooling of a central air conditioner or heat pump (in Btu) during the normal cooling season as compared to the total electric energy input (in watt-hours) consumed during the same period..."

For purposes of the ENERGY STAR program, Central Air Conditioner is defined as the combination of both indoor and outdoor components and you should have received an ENERGY STAR SEER number for that whole system.

Definition of Central Air Conditioner: A central air conditioner model consists of one or more factory-made assemblies which normally include an evaporator or cooling coil(s), compressor(s), and condenser(s). Central air conditioners provide the function of air-cooling, and may include the functions of air-circulation, air-cleaning, dehumidifying or humidifying. [1]

But unless your central air conditioning system is a "Matched Assembly" [defined below], it is likely that the SEER definition for your central air conditioner does not address the confusion that can arise when your inside unit air handler (which includes the evaporator or cooling coil you mention) and compressor/condenser (the outside unit) may have separate individual SEER ratings. Each of those two major system components will be on or off (running or not) at different times during a cooling cycle, depending on a variety of factors.

Matched Assembly [central air conditioning or heat pump system]: A matched assembly is a model combination that is listed in the ARI Directory of Certified Equipment or for which the manufacturer has published energy efficiency data that includes rated SEER and EER levels, and in which both the condenser unit and evaporator coil are installed simultaneously. A matched assembly shall also include the air handler, furnace, or other component that is used to determine the rating according to ARI 210/240.

If your installer did not install a Matched Assembly central air conditioning system, and if the installer did not provide you with documentation [not just an oral statement or claim] of the overall SEER rating for your central air conditioner, to obtain a SEER rating for the combined system you'd need to consult the manufacturer and make some assumptions about the on-off time of each of these components.

For combinations of air handlers and compressor/condenser units intended to be sold as a complete, installed, system, the manufacturer may be able to give you an overall SEER rating for that system.

Or maybe not not. Given the Energy Star definition of Central Air Conditioners and SEER (see SEER RATINGS & OTHER DEFINITIONS), it it would not be accurate to simply add a few SEER points to the compressor/condenser unit's SEER based on an opinion about other system components. Nor are component SEER ratings additive - you don't just add them together to get an overall system SEER. Not without the manufacturer's agreement.

We can save some potential embarrassment - don't assume your installing company has been dishonest (as you put it) without first asking the manufacturer for clarification.

The U.S. Government's Energy Star Program's discussions and documents about the SEER rating program (and SEER targets for newly installed equipment) suggests that folks in both government and industry are aware that the lack of clarity or of technical details in SEER rating definitions is a source of potential misunderstandings between consumers and their installing contractors. [2]

Notice that for a split system air conditioning system, the ENERGY STAR definition is more clear about the necessity to combine the major components in arriving at a SEER rating, as it refers explicitly to the ... actual condenser-evaporator coil combination of the split system.

Definition of Split System [air conditioner or heat pump system]: A split system is an ASHP or central air conditioner with separate indoor (evaporator) and outdoor (condenser) units. For split systems, the energy-efficiency rating of a particular split system is based on the actual condenser-evaporator coil combination of the split system. [1]

Also for completeness we include:

Gas/Electric Package [Combined Air Conditioning & Heating] Unit: A single package unit with gas heating and electric air conditioning that is often installed on a slab or roof.[1]

Also see ENERGY STAR PROGRAM and for tips on how to cut air conditioning or heat pump operating costs, see AIR CONDITIONING HEAT PUMP SAVINGS.

Question: What does 20 Amps mean?

What does 20 amps actually mean - Mary Riccio

Reply: ... it depends. Amps is a measure of electrical current that we elaborate here:

In a residential electrical circuit, a 20-amp rated circuit means that the electrical wire and it's overcurrent protection (fuse or circuit breaker) are rated for a total load or total current draw of 20 amps. The sum of all of the electrical current drawn by everything connected to that circuit must be 20-Amps or less - else the circuit breaker will trip or fuse will blow to prevent overheating of the wire (and a fire hazard).

Definitions of AMPS and other electrical terms can be found at InspectAPedia either by using the search box found at the top and bottom of our pages, or by clicking on the ELECTRICAL link found at page top or page bottom. On our ELECTRICAL page you'll see at page left, a link to DEFINITIONS OF ELECTRICAL TERMS.

Quoting from that article's "Definition of Amps, Electrical Current",

Amperage or Amps provided by an electrical service is the flow rate of "electrical current" that is available. Mathematically, Amps = Watts / Volts. (Amps = Watts divided by Volts)

Speaking practically, the voltage level provided by an electrical service, combined with the ampacity rating of the service panel determine how much electrical demand, or in another sense how many electrical devices can be run at one time in the building.

Depending on what you are looking at, 20-Amps may be the rating of a particular piece of equipment. For example a 20-Amp circuit breaker means that that safety device will limit to 20 Amps the current drawn on the circuit that it is protecting. If you plug three 10-amp electric heaters into that circuit and they all are running simultaneously, their combined current draw (3 x 10 = 30Amps) should trip the circuit breaker and turn off the circuit to protect it from overheating and a possible fire.

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AIR CONDITIONING & HEAT PUMP SYSTEMS

A/C - HEAT PUMP CONTROLS & SWITCHES
A/C DATA TAGS
A/C - HEAT PUMP CRITICAL DEFECTS
A/C DIAGNOSTIC FAQs
A/C REFRIGERANTS
A/C TYPES, ENERGY SOURCE
AGE of AIR CONDITIONERS & HEAT PUMPS

AIR CONDITIONER BTU CHART
AIR CONDITIONER COMPONENT PARTS
AIR CONDITIONER TYPES, ENERGY SOURCES
AIR CONDITIONER NOT WORKING

AIR FILTERS for HVAC SYSTEMS

AIR HANDLER / BLOWER UNITS
APPLIANCE EFFICIENCY RATINGS
BACKUP HEAT for HEAT PUMPS

BLOWER DOORS & AIR INFILTRATION
BLOWER FAN CONTINUOUS OPERATION
BLOWER FAN OPERATION & TESTING

BOOKSTORE - Air Conditioning "How To" Books

CAPACITORS for HARD STARTING MOTORS
CAPILLARY TUBES
CLEANING & Legionella BACTERIA
COMPRESSOR & CONDENSING COIL, A/C

CONDENSATE HANDLING, A/C
CONDENSATION or SWEATING PIPES, TANKS
COOL OFF HEAT Thermostat Switch
COOLING CAPACITY, RATED
COOLING COIL or EVAPORATOR COIL
DATA TAGS on AIR CONDITIONERS
COMBUSTION GASES & PARTICLE HAZARDS
CONDENSING BOILERS/FURNACES
CONDENSING BOILERS/FURNACES DAMAGE
COOLING COIL or EVAPORATOR COIL
COOLING LOAD REDUCTION by ROOF VENTS
CRITICAL DEFECTS on A/C SYSTEMS

DATA TAGS on AIR CONDITIONERS
DEFINITION of Heating & Cooling Terms
DEFINITIONS of ELECTRICAL TERMS
CONDENSATION or SWEATING PIPES, TANKS
COOLING LOAD REDUCTION by ROOF VENTS

DEHUMIDIFICATION PROBLEMS
DEW POINT CALCULATION for WALLS
DEW POINT TABLE - CONDENSATION POINT GUIDE

DIAGNOSE & FIX AIR CONDITIONER / HEAT PUMP

DUCT SYSTEM & DUCT DEFECTS
DUCTS - Asbestos
DUCT INSULATION, Asbestos Paper
DUCT INSULATION for SOUNDPROOFING
DUCT SYSTEM NOISES
DUCTS, Asbestos Transite Pipe
DUST CONTAMINATION FROM HVAC?

EDUCATION, HVAC SCHOOLS
ELECTRIC MOTOR DIAGNOSTIC GUIDE
ELECTRIC MOTOR OVERLOAD RESET SWITCH
ELECTRICAL POWER SWITCH FOR HEAT

ENERGY SAVINGS in buildings
EVAPORATIVE COOLING SYSTEMS
EVAPORATOR COIL or COOLING COIL
EXPANSION VALVES, REFRIGERANT

FAN, AIR HANDLER BLOWER UNIT
FAN AUTO ON Thermostat Switch
FAN CONVECTOR HEATERS - HYDRONIC COILS
FAN LIMIT SWITCH
FAN NOISES

FURNACES WARM AIR HEATING SYSTEMS

GASES, EXPOSURE, TESTING
  Carbon Dioxide - CO₂
  Carbon Monoxide - CO
  METHANE GAS SOURCES
GAS MEASUREMENT TOOLS
GAUGE, REFRIGERATION PRESSURE TEST

HEAT LOSS (or GAIN) in buildings
HEAT PUMPS

HUMIDITY LEVEL TARGET

INDOOR AIR QUALITY IMPROVEMENT GUIDE
INSPECTION LIMITATIONS
LEED GREEN BUILDING CERTIFICATION

LOST COOLING CAPACITY

MANUALS & PARTS GUIDES - HVAC
MOTOR OVERLOAD RESET SWITCH

NOISY AIR CONDITIONER / HEAT PUMP
NOISE / SOUND DIAGNOSIS & CURE
  Air Leak Noises
  AIR CONDITIONING & HEAT PUMP NOISES

OPERATING COST
OPERATING DEFECTS
OPERATING TEMPERATURES

PORTABLE ROOM AIR CONDITIONERS
PRESSURE READINGS, REFRIGERANT

REPAIR GUIDE, AIR CONDITIONERS / HEAT PUMPS
REPAIR & DIAGNOSTIC FAQs for A/C

REFRIGERANTS
RETROFIT SIZING for A/C or HEAT PUMPS

SEER RATINGS & OTHER DEFINITIONS
  SEER RATING HISTORY
SYSTEM OPERATION
SWAMP COOLERS

THERMOSTATS, HEATING / COOLING
THERMOSTATIC EXPANSION VALVES

WATER COOLED AIR CONDITIONERS

• Thanks to Mark Cramer, Tampa Florida, for assistance in technical review of the "Critical Defects" section and for the photograph of the deteriorating gray Owens Corning flex duct in a hot attic. Mr. Cramer is a Florida home inspector and home inspection educator.
• Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• [1] U.S. Government EnergyStar Program, ENERGY STAR Program Requirements for ASHPs and Central Air Conditioners – FINAL DRAFT, found at http://www.energystar.gov/ia/partners/prod_development/revisions
  /downloads/ac_ashp/Final_Draft_CAC_ASHP_Eligibility_Criteria.pdf
• Air-Conditioning and Refrigeration Institute. Standard 210/240 “2003 Standard for Unitary Air-Conditioning and Air-Source Heat Pump Equipment.”
• [2] SoCalEdison Comments for ASHP/CAC Options Paper, Web search 07/22/2011 - SoCalEdison.pdf, note that by its name this article contains comments by a representative from SoCalEdison in response to a request for input to help EnergyStar develop an HVAC standard for 2006, but neither addressee nor writer are fully identified. SoCalEdison is an acronym for Southern California Edison, an Edison International Company and one of the largest electric utilities in the United States. According to SoCalEdison, "Residential and commercial air conditioning is responsible for the largest share of peak [electrical energy] demand in California,contributing approximately 33% of peak demand." [citation:
  http://asset.sce.com/Regulatory/Energy%20Efficiency%
  20Filings/SCE2507COMPREHENSIVEHVAC.pdf ] - also see the Kema -Xenergy energy use citation just below.
• Kema -Xenergy, “California Statewide Residential Sector Energy Efficiency Potential Study,” April 2003,
  and Kema-Xenergy, “California Commercial Sector Energy Efficiency Potential Study,” July 2002. Base
  information is factored by 0.367 to get SCE portion of savings.
• Thanks to Scott at SJM Inspect for suggesting this EPA document and for technical editing remarks regarding our air conditioning website, SJM Inspection Service LLC, serves the entire state of CT, sjminspect@optonline.net 203-543-0447 or 203-877-4774 5/16/07
• Thanks to reader Michael V. for commenting on watt, volt, amp calculations, August 2009.
  
• Thanks to reader Daniel Mann, P.E. for commenting on W=VxI and the power factor or PF, February 2010
• Thanks to reader Robert for pointing out a typographical error in our latent heat of vaporization of water to steam at 212 degF, September 2010
• Refrigeration License Examinations, 2nd Ed., A Complete Guide to the Written and Practical Exams, Antonio Mejias, Arco, ISBN-10: 0768910196, ISBN-13: 978-0768910193p. 130: BTU Concepts cites the latent heat of vaporization and 970 btus.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
• Complete List of Air Conditioning & Heat Pump Design, Inspection, Repair Books at the InspectAPedia Bookstore.

• Modern Refrigeration and Air Conditioning, A. D. Althouse, C.H. Turnquist, A. Bracciano, Goodheart-Willcox Co., 1982
• Principles of Refrigeration, R. Warren Marsh, C. Thomas Olivo, Delmar Publishers, 1979
• "Air Conditioning & Refrigeration I & II", BOCES Education, Warren Hilliard (instructor), Poughkeepsie, New York, May - July 1982, [classroom notes from air conditioning and refrigeration maintenance and repair course attended by the website author]
• Refrigeration and Air Conditioning Technology, 5th Ed., William C. Whitman, William M. Johnson, John Tomczyk, Cengage Learning, 2005, ISBN 1401837654, 9781401837655 1324 pages
• Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment ($69.00 U.S.).
• Air Conditioning Inspection, Diagnosis, Repair, Efficiency all the basics for home owners, inspectors, new repairmen
• Air Conditioning SEER - New DOE Air Conditioner and Heat Pump Efficiency Standard
• Asbestos HVAC Ducts and Flues field identification photos and guide
• Fiberglass: Indoor Air Quality Investigations: Fiberglass in Indoor Air, HVAC ducts, and Building Insulation