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InspectAPedia ® Home AIR CONDITIONING & HEAT PUMP SYSTEMS A/C - HEAT PUMP CONTROLS & SWITCHES AIR CONDITIONER COMPONENT PARTS AIR CONDITIONER TYPES, ENERGY SOURCES AIR FILTER EFFICIENCY AIR FILTERS, FIBERGLASS PARTICLES AIR FLOW MEASUREMENT CFM APPLIANCE EFFICIENCY RATINGS 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 CHINESE DRYWALL HAZARDS CONDENSATION or SWEATING PIPES, TANKS DEFINITION of Heating & Cooling Terms DEW POINT CALCULATION for WALLS DEW POINT TABLE - CONDENSATION POINT GUIDE DIAGNOSE & FIX AIR CONDITIONER / HEAT PUMP DIAGNOSE & FIX HEATING PROBLEMS-BOILER DIAGNOSE & FIX HEATING PROBLEMS-FURNACE DUCTS - Asbestos DUCT INSULATION, Asbestos Paper DUCT INSULATION for SOUNDPROOFING DUCT SYSTEM NOISES DUCTS, Asbestos Transite Pipe DUST, HVAC CONTAMINATION STUDY ELECTRIC MOTOR OVERLOAD RESET SWITCH EVAPORATIVE COOLING SYSTEMS FAN LIMIT SWITCH FAN NOISES GAS EXPOSURE EFFECTS, TOXIC GAS DETECTION INSTRUMENTS HEAT LOSS (or GAIN) in buildings HEAT LOSS (or GAIN) INDICATORS HEAT LOSS R U & K VALUE CALCULATION HEAT PUMPS HEATING SMALL LOADS INSPECTION CHECKLIST - OUTDOOR UNIT INSPECTION LIMITATIONS, A/C SYSTEMS LEED GREEN BUILDING CERTIFICATION LOST COOLING CAPACITY LOW VOLTAGE TRANSFORMER TEST MOTOR OVERLOAD RESET SWITCH MOLD in AIR HANDLERS & DUCT WORK OPERATING COST, AIR CONDITIONER OPERATING DEFECTS, AIR CONDITIONING REPAIR GUIDE, AIR CONDITIONERS / HEAT PUMPS REPAIR & DIAGNOSTIC FAQs for A/C SWAMP COOLERS THERMOSTATS, HEATING / COOLING THERMOSTATIC EXPANSION VALVES WATER COOLED AIR CONDITIONERS WINDOW / WALL AIR CONDITIONERS WINDOW / WALL A/C SUPPORTS More Information |
This article discusses exactly how and where to measure input and output air temperatures at air conditioning equipment in order to determine whether or not it is operating properly, as part of checking basic air conditioning system operation and for detection of air conditioning operating defects. An introduction to air conditioner temperatures and some rules of thumb that are quick and easy to apply in diagnosing air conditioner problems are provided at the preceding article: Air Conditioning System Temperatures. Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman. Procedures for Making Temperature Measurements of Air Conditioning SystemsAir conditioner temperatures that are too high or too low can indicate specific operating problems on central and portable or window air conditioners. Simple measurements of air temperatures, if made at the right place, can assist in diagnosing what may be wrong and what repairs may be needed for the air conditioner. This document is a portion of our website which describes the inspection of residential air conditioning systems (A/C systems) to inform home buyers, owners, and home inspectors of common cooling system defects. If your air conditioning or heat pump system has lost its cooling capacity or won't start see REPAIR GUIDE for AIR CONDITIONERS. See How to determine the cooling capacity of air conditioning equipment if the system seems to be working but is inadequate to cool your building. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. Refrigeration and Air Conditioning Theory: Refrigeration systems rely on two state changes of the refrigerant: gas to liquid, and liquid back to a gas to move sensible heat from the low side of the air conditioning system to the high side. At the evaporator coil heat (BTUs) is absorbed when the refrigerant evaporates (liquid to gas), and at the condenser coil heat is released during condensation (gas to liquid). R12 refrigerant has a boiling point of -21 degF (change of state from liquid to gas vapor) and R22 has a boiling point of -41 degF. But if you are measuring air temperature close to the evaporator coil or condenser coil you won't record these two temperatures on your thermometer. Rather the temperature that you can record will be significantly affected by ambient conditions. For example, at the evaporator coil the temperature of indoor air entering the coil, the distance between the coil surface and the thermometer, the air velocity, and other factors will produce a temperature reading that is different from and certainly higher than the boiling point of the refrigerant entering the coil. While we may form an opinion about just how cool the air should be right at an evaporator coil, or inside of an air handler supply plenum, most diagnostics look for temperature differences between air entering the air handler and air leaving the air handler to evaluate what's going on in the system. NOTE: an air conditioning technician has more precise tools to evaluate the condition of a system such as gauges to measure the pressures on the high side and low side of the system and an ammeter to measure current draw of the compressor. How to Examine Air Conditioner TemperaturesTemperature Measurements & Observations at the Room ThermostatAir conditioner thermostat settings: observe the settings on the wall-mounted room thermostat (assuming you've already
established that the switches and controls have turned the system on and that it is in cooling mode and has
been operating for half an hour or longer. Temperature Measurements at the Evaporator Coil in the Air Handler![]() How to Measure Air Conditioning Register outlet temperatures using a dial thermometer probe:
we simply wedge the probe of our dial thermometer between the
vanes of a ceiling supply register, or drop it probe-first through the slots of a cool-air supply floor register
where we leave it for at least five minutes. Sketch courtesy of Carson Dunlop Associates. We use tissue or toilet paper to confirm for skeptical owners that
the direction of air flow is "in" at a return register and "out" at a supply register since sometimes this
can be confusing to a novice. Measuring Air Conditioning Duct temperatures using a dial thermometer probe: if there is not an existing duct opening such as a foil-covered hole or a removable plug, we drill a 1/4" diameter hole in the sheet metal of the duct. BE CAREFUL not to drill where you can damage a refrigerant line, coil, wire, etc. After inserting the probe into the hole for measurement, waiting, taking our measurement, we close the hole using a square of adhesive foil tape, duct tape, or snap-in plugs sold for that purpose. Temperature Measurements at the Condensing Coil & Fan/Compressor UnitMeasuring temperatures at an Air Conditioning Compressor: By holding the thermometer's probe in any air path (and patience) it is trivial to measure ambient air temperature, air temperature flowing into the condenser unit at the condensing coils, and temperature flowing out of the condenser at its fan output (keep the probe out of the blades!) Measuring Air Conditioning Temperatures Using an Infrared Thermometer: permits measurement of
surface temperatures such as the surface of a metal duct (is it insulated?), surfaces of
refrigerant suction and high pressure lines (do we know target temperatures?), or surfaces inside
a building. Frequently Asked Questions (FAQs)No FAQs have beenn posted for this topic. Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia. Ask a Question or Search InspectApediaUse the search box below to ask a question or to search the InspectApedia.com website. Ask a Question or Enter Search Terms in the InspectApedia search box just below. Technical Reviewers & ReferencesRelated Topics, found near the top of this page suggest articles closely related to this one. Click to Show or Hide Citations & References
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