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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 DIAGNOSIS & REPAIR
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
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
DIAGNOSTIC GUIDES A/C / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DUCTS - Asbestos
DUCT INSULATION, Asbestos Paper
DUCT INSULATION for SOUNDPROOFING
DUCT SYSTEM & DUCT DEFECTS
DUCT SYSTEM NOISES
DUCTS, Asbestos Transite Pipe
DUST, HVAC CONTAMINATION STUDY
ELECTRIC MOTOR OVERLOAD RESET SWITCH
EVAPORATIVE COOLING SYSTEMS
FAN LIMIT SWITCH
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
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 GUIDES A/C / HEAT PUMP
REPAIR & DIAGNOSTIC FAQs for A/C
THERMOSTATS, HEATING / COOLING
THERMOSTATIC EXPANSION VALVES
WATER COOLED AIR CONDITIONERS
WINDOW / WALL AIR CONDITIONERS
WINDOW / WALL A/C SUPPORTS
How to choose an air conditioner for window or through-wall mounting, how much BTU capacity do you need? Also see COOLING RULES OF THUMB to guesstimate how many tons or BTUs of cooling a building needs and see RATED COOLING CAPACITY to determine the cooling capacity of existing air conditioning equipment.Our page top photo shows the front of a Haier portable room air conditioner. Not shown are condensate accumluator or ductwork/hose extending to outside.
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Portable air conditioners - units on wheels which are plugged into an outlet but can be moved room-to-room and do not require a window for their exhaust. These cooling units are of modest cooling ability, typically around 10,000 BTUh though some producers such as Sunpentown offer units up to 14,000 BTUh. See RATED COOLING CAPACITY for an explanation of how to determine the cooling capacity of an air conditioner that is already installed at a building. There are quite a few brands of portable room air conditioners, including Fredrich, Haier, New Air, Sharp, Soleus, Supentown, SPT (shown at left). [InspectAPedia.com has no financial nor any other relationship with any brand or product discussed at this website.]
The U.S. ENERGY STAR program uses the term "Single Package" air conditioning system which is defined as follows:
Single Package: A single package unit is an ASHP or central air conditioner that combines both condenser and air handling capabilities in a single casing.
In this definition, ASHP refers to an Air-Source Heat Pump (ASHP) which is further defined as follows:
Question: How can I Avoid Mixing Outdoor Air Into My Room Air with a Window or Portable Air Conditioner?
Do you know of any air conditioners (besides mini split ac's) that don't mix inside air with outside air? Do you know of any ac's that have sealed compressors?
If not, do you know of a solution to not mixing inside with outside air? Do regular window ac's and dual hose portable ac's normally mix inside with outside air? - B.R.
Reply: Close the outside air intake vent on a window air conditioner unit or use a portable room air conditioner
It sounds as if you've been given some confusing information. All residential A/C compressors are sealed units, and outdoor air has no role in the internal operation of the compressor.
Room air conditioners typically have a manual control that permits mixing in outside air or shutting it off.
Central air conditioner systems do or do not have outside air supplied to the return duct system depending on the duct design, having nothing to do with the compressor you cited. Though many residential central air systems we've inspected do not provide for outside air or makeup air, it's a good component to add to the design for a very tight house where IAQ could be a worry; for maximum heating or cooling efficiency we use an air to air heat exchange where outdoor air is entering the system.
How to Close off Outside Air Intake for Window-mounted or Through-Wall Air Conditioners
If you are using a window-mounted or through-wall mounted air conditioner, it is likely to have a mechanical control, a dial or lever that opens or closes a vent that mixes or stops mixing some outside air with room air as it is circulated through the air conditioner unit.
If you don't want to introduce outdoor air (increasing the cooling and dehumidification effectiveness of the system at the expense of fresh air), just be sure that your unit's outside air control is in the "closed" position. These vents may not be perfectly air tight but in a modern air conditioner closing the vent will close off nearly all outside air intake.
Outside Air & Portable Air Conditioners
While some portable air conditioners may make use of outside air to assist in cooling their compressor and in removing condensate, at least some of the models, including dual-hose units that we read about (which is certainly not all of them) provided an outside air intake that adds outside air to the room air being cooled and dehumidified.
The balance point between maximizing the cooling ability (and reducing cooling costs) any air conditioner by closing off outside air from the system and the quality of indoor air in a tight building needs to be decided on a case-by-case basis. If your building is very tight, or has odors, stale air, or high dust or allergen levels see INDOOR AIR QUALITY IMPROVEMENT GUIDE.
FAQS & Properties of Portable Air Conditioners
One producer of portable air conditioners who provides particularly helpful description of the operating properties of these devices is Sunpentown International (SPT), a California firm. Here are some relevant FAQs that give insight to the operation and use of portable air conditioners, as well as comparing the use of single-hose and dual-hose portable room air conditioners. The photo at left shows typical flexduct and other accessories for a portable room air conditioner, in this case from Soleus.
Quoting from Sunpentown's FAQs (Quoting and paraphrasing):
NOTE about outdoor air: We read no indication in either design that outdoor air is added to or mixed in with room air.
More detail about how to diagnose and cure an air conditioner that is not dehumidifying can be found at Air Conditioning Dehumidification Problems.
Role of Exhaust Flex-Duct or "Hose" for Portable Room Air Conditioners
Our photo (left) shows huge portable air conditioning systems that are being used to air condition an enormous tent used for a college alumnae gathering in New York. The white flex duct you see there is blowing cool air into the tent space and the entire air conditioner is located outside the tent. This is a "total loss" system that pulls outdoor in to the unit, cools it, and blows it into the tent.
In comparison with the commercial outside portable air conditioner supply flex duct you see at left, indoor portable air conditioners provide for an exhaust duct as follows:
All portable AC units require exhaust hose installation. This is for removal of hot air which has been used to cool off the compressor. Standard installation includes venting through a sliding window or through the wall, by cutting a hole. Sunpentown AC units are supplied with the necessary accessories for either installation: flexible hose (extends up to 5'), window kit and wall adapter.
[End of quote, paraphrase]
Portable, window, or through-wall air conditioners are typically described by their manufacturer as suited for:
To determine the BTUs needed to cool a given space follow this procedure:
The Air Conditioner BTU Recommendation table found at AIR CONDITIONER BTU CHART gives recommended air conditioning BTU's necessary to cool a single room. The data in the table assumes that the ceiling over the room is insulated and that the room is not over or is not itself a special heat-producing area such as a kitchen or boiler room. Do not buy an air conditioner which is oversized (too many BTUh) for the area you need to cool. You may think that bigger is better, but not in the case of air conditioning.
To make a room comfortable the air conditioner needs to both cool the room air AND dehumidify the room air.
If the air conditioner is too large for the space to be cooled, the temperature will drop quickly and the A/C unit will shut off before the air has become adequately dry.
The room will be either too cold or too humid for comfort.
How Much Cooling Capacity do we need Per Square Foot of Building Area? How Much Space can a Ton of Cooling Capacity Serve?
Maybe 450 sq.ft. to 1000 sq.ft. of a typical home can be cooled per ton of cooling capacity: that is, one ton (or 12,000 btuh) of air conditioning can cool about 500 sq.ft. of space. Sketch courtesy of Carson Dunlop Associates.
But the real answer is, it depends. Some of the factors that affect the ability of an air conditioner to cool a space need to be considered besides just the number of square feet. These include at least the following questions about air conditioning load and cooling requirements:
Other types of portable or individual-area air conditioners
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