Swamp Coolers & Evaporative Coolers for Air Cooling: Design & Usage Guide
EVAPORATIVE COOLING SYSTEMS - CONTENTS: Guide to Swamp coolers or Evaporative Coolers for building cooling. Evaporative cooling systems for homes. Design specifications for cooling systems with under-floor air ducts. Solar Age Magazine Articles on Renewable Energy, Energy Savings, Construction Practices
POST a QUESTION or READ FAQs about using a swamp cooler to cool a building interior - when do swamp coolers work better than an air conditioner?
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This article explains the use of an evaporative cooling system or "swamp cooler" including cool air delivery design considerations when using under-floor ducts for cool air delivery in buildings. Swamp coolers or evaporative cooling systems work well in dry climates - usually, as we explain here. The discussion of cool air duct location and routing includes general air conditioning duct design concepts that also apply to all air conditioning and cooling designs.
Evaporative Cooling Systems or "Swamp Coolers" - How They Work
Evaporative coolers, also called "swamp coolers" rely on the evaporation of water to cool building air, rather than the movement of a refrigerant through cooling coils.
Cooling towers, swamp coolers, and even a simple window fan blowing air across a pan of water and into a room are types of evaporative cooling systems.
[Click to enlarge any image]
Swamp coolers systems may use less energy than a refrigerant-gas and compressor type air conditioner but they'll only work where the ambient humidity is low enough to make it easy to evaporate water, such as in Arizona and other areas of the Southwest and Mexico.
Our sketch (left), courtesy of Carson Dunlop, shows three types of evaporative cooling systems or "swamp coolers".
All three evaporative cooling system approaches are similar: dry outdoor air is blown across an evaporative cooling device that uses water evaporation to cool the incoming air.
The differences among these swamp cooler designs are principally how the water to be evaporated is delivered to the evaporative cooling device (drum or pad bottom is immersed in a water reservoir pan, or a pump delivers water to the top of the evaporative pad), and the type of evaporative device itself: a rotating drum or an evaporative pad.
Delivery of Cool Air Using an Evaporative Cooling System
The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.
Topic: Under-floor ducts for cool air delivery with (for example) an evaporative cooling system
Question: We plan to build a pilot energy-efficient home in our city. We have a long and somewhat severe cooling season, with a humidity level that is relatively low (10-15 % RH). An evaporative cooling system or swamp cooler should suffice, but there are several drawbacks: dust, open windows, safety, noise, and the like.
I would like to duct the cool air delivery system under a wood-framed floor, supplying cool air through floor registers, and exhausting it out through a roof cupola. (See sketch above, courtesy of Solar Age Magazine). I am sure that an attic fan will be necessary to drive the warm air exhaust out of the building.
Do you see any obvious problems with the scheme I have described? -- Jimmy Moore, Odessa, TX
Single-stage direct evaporative coolers, also called "swamp coolers" do provide a cost-effective means of cooling houses during hot, dry periods. Their main drawback is moister indoor air - the cost for a lower dry-bulb temperature.
Due to low energy use (for a small fan and water pump), swamp coolers are popular in the U.S. in parts of the West and Southwest. For example, our photograph at page top shows a swamp cooler system whose operating components are mounted on a Tucson Arizona rooftop.
Delivering Cool Air Through Floor Ducts?
Delivering cooled air through the floor and exhausting it through the roof runs counter to the tendency of warm air to rise and cool air to fall in a building. But an exhaust fan in the roof should pull air upwards through the entire house.
Watch out: Two warnings:
Make sure that the exhaust fan capacity in cubic feet per minute (CFM) is matched to the volume of air that is being supplied from the cooling system upwards from the floor ducts and air registers.
Carson Dunlop's sketch (left) shows a different approach for a closed air duct system that changes its duct operation depending on whether warm air or cool air is being delivered into the building.
You would probably not use this duct design in an evaporative cooling system because the evaporative cooling approach depends on continuous introduction of dry outside air into and through the building during the cooling system, but the sketch makes clear a duct system intended to deliver cool air in a building needs to operate differently than ducts intended to deliver warm air during the heating system if airflow is to be optimized.
Using a Rooftop Cupola to Exhaust Swamp Cooler-Delivered Cool Air?
Provide an air duct between the top floor ceiling grille and the roof exhaust cupola. This will keep moist (and possibly cooler) air out of the attic, where it might condense at night and cause moisture problems in the structure and in the attic insulation.
Carson Dunlop's sketch (left) warns of another safety consideration: a whole house fan or an attic exhaust fan (such as we describe above), can cause back-drafting at fireplaces and atmospheric-vented gas heating appliances - backdrafting can in turn cause dangerous, potentially fatal carbon monoxide hazards in buildings.
Finally, remember to provide a means of closing off the rooftop exhaust during the heating season. Otherwise your warm house air will simply escape by natural convection currents carrying it up and outdoors through your rooftop-mounted exhaust system even if the fan is not running.
See Solar Age Magazine "Notebook" 2/84, for the conditions where evaporative cooling is effective.
In that issue, author Jerry Germer reviews use of the psychrometric chart that relates moisture, temperature, and indoor relative humidity to discuss the conditions that make people comfortable indoors, and how to relate indoor comfort to the outdoor climate, particularly to temperature and humidity in those two environments.
Our photo (left) shows an evaporative cooler or "swamp cooler" in use blowing cool air into an outdoor mechanic's work area at Canyon Auto Sales in Tucson, AZ. Photo by the author and Andy Gieseke, Canyon Auto.
Swamp coolers or other evaporative cooling systems can cool a building interior using less energy than a conventional air conditioner or heat pump system except during times of very wet or humid weather such as the "monsoon" season in southern Arizona.
During wet and very humid weather evaporative cooling simply cannot evaporate enough water to produce good cooling. Some building owners install both evaporative cooling or swamp coolers and a conventional refrigerant-based air conditioner or heat pump, running the latter only when necessary due to humid conditions.
Watch out: leaky swamp coolers or just about any mechanical equipment that regularly spills or overflows water onto a roof surface is likely to cause stains on the roof surface and might lead to roof wear as well.
Mr. Germer mapped eight heating and cooling "design zones" onto areas of the psychrometric chart and then described eight indoor air conditioning approaches and related them to the outdoor climate. For areas or times of the year when temperature and humidity outdoors, and thus also relative humidity, fall within multiple zones on the Germer chart, multiple of the 8 zones and 8 indoor air conditioning strategies below might be usable.
Active solar or mechanical heating: this zone has outdoor temperatures too low for passive building environment conditioning strategies.
Dehumidification: high outdoor (or indoor) humidity requires using some method to remove the excess humidity in order for building occupants to be comfortable. In the 1984 article Germer pointed out that passive dehumidification had not been well developed. See HUMIDITY LEVEL TARGET.
Mechanical air conditioning: temperature & humidity combinations in this climate zone cannot be managed by passive means and so mechanical air conditioning
See AIR CONDITIONING & HEAT PUMP SYSTEMS or active solar cooling will be needed.
Ventilation: although temperatures and humidifies may be high, occupants may be made comfortable by direct evaporation of sweat from the skin if enough air velocity is available - in other words, fans can do the trick.
Thermal mass: these air conditioning systems are usually found in hot-dry climates with dry cool nights, such as southwestern United States and parts of Mexico, particularly at higher elevations (see PASSIVE SOLAR DESIGN METHOD and see THERMAL MASS in BUILDINGS
well as THERMAL MASS in UPSTAIRS). Radiant cooling and night-flushing of internal mass with cool outside air stores coolness (the ability to later absorb heat) for the next day, and similarly, during the warmer day, the same thermal mass can store warmth to even out cooler nighttime temperatures indoors.
Evaporative cooling: low energy "swamp coolers" (discussed in this article) can be used under conditions of low humidity such as in Arizona and higher elevations of Mexico.
Humidification: moisture needs to be added to very dry air for indoor comfort.
See HUMIDITY LEVEL TARGET. We prefer local or room humidifiers after seeing duct, mold, concerns with some centralized humidifier add-ons to heating and air conditioning systems.
The link to the original Q&A article in PDF form immediately below was preceded above by an expanded/updated online version of this article.
The articles at this website describe the basic components of an air conditioning system
and then we discuss how to estimate the rated cooling capacity of an air conditioning system by examining various data tags and components.
The limitations of visual inspection of A/C systems are described.
Evaporative Cooling Resources for Products, Manuals, Installation Guides
Breezair Corporation, Seeley International Americas
1202 North 54th Avenue
Building 2 Suite 117
Phoenix Arizona 85043
United States of America
Phone: 602-353-8066, Website: www.breezair.com
Breezair provides owners manuals, installation guides, and technical support for evaporative cooling systems
Quoting from the Braemar website (see links below), Seeley International
now exports to well over 120 countries. Not bad for a
company that started out in 1972 in the garage of its
founder and Executive Chairman, Frank Seeley
New Zealand, email email@example.com, Tel: 0800-488-522 Website: www.bonaire.com.au
Braemar evaporative cooling systems, (Seeley International - see above), Tel: 1300-360-815 in Australia, website: http://www.braemar.com.au
Brivis, evaporative cooling systems,
61 Malcolm Road
Braeside Victoria 3195
(1300 274 847)
Fax: +61 (03) 9264 9400
email: firstname.lastname@example.org Website: www.brivis.com.au
Brivis New Zealand
Distributor: Warm Air Ltd
69 Marsden Street
Lower Hutt 5010 New Zealand
PO Box 38523
Wellington Mail Centre
Wellington 5043 New Zealand
(0800 9276 247)
Ph: +64 (04) 920 1670
Fax: +64 (04) 920 1681
Brivis South Africa
Distributor: Lorenz and Associates
Northlands Deco Park
Cnr Witkoppen and Newmarket Roads
North Riding, Johannesburg South Africa 2194
(0861 274 847)
Ph: +27 (011) 704 6112
Fax: +27 (011) 704 0022
Continue reading at ROOFTOP A/C / HEAT PUMP - the air conditioning system seems to be "running" but not enough cool air, or no cool air at all is being delivered to the occupied space, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Evaporative coolers are either roof-mounted (whole house cooling systems) or mounted in a window (smaller units) so are positioned differently than refrigerant-based cooling systems using an indoor air handler and outdoor compressor/condenser unit. An important consideration in mounting the rooftop unit is the proper selection of and strength of the supporting roof jacks.
But a look through the installation and owners manuals for six evaporative coolers (listed in the article above) I did not find any references to side clearances or top clearances for the units, perhaps because of their anticipated location. Certainly it would make sense to avoid installing a rooftop unit where you'd expect trouble such as
- Don't install any fan operated or air cooled device where its air intake or outlet are obstructed by a nearby vertical wall, chimney, or other exhaust system
- Don't install any fan-operated or air-cooled component where its intake air or outlet air compete with another such unit installed close-by - lest hot exhaust from one unit increase the temperature of the incoming air in another unit.
OPINION: if you don't see other specific clearance distances in the installation guide for your particular system, check with the manufacturer for advice. A general safe rule is probably to keep at least 2 meters of separation between nearby air operated devices and at least one meter from a vertical or enclosed overhead surface.
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 "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]
 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.
 Thanks to Jon Bolton, an ASHI, FABI, and otherwise certified Florida home inspector who provided photos of failing Goodman gray flex duct in a hot attic.
 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.com 203-543-0447 or 203-877-4774
 Thanks to Joe Panimondo for technical editing, April 2011
 This website discusses these air conditioning and heat pump terms and problems: Air Conditioners: Central Air Conditioning Troubleshooting & Repair Guide: How to Inspect, Diagnose, & Repair Central Air Conditioning: Defects in A/C compressors, air handlers, duct work, and controls. We explain how to inspect & repair central air conditioning systems and for homeowners we also answer basic HVAC questions such as what are the basic air conditioning components? We provide guidance in determining air conditioning cooling capacity & energy efficiency, Troubleshooting air conditioning compressor problems, Diagnosing air conditioning air handler problems, Air conditioning condensate problems, Duct system inspections, defects, repairs, Cleaning air conditioning equipment & A/C refrigerants.
 HVAC brands discussed include but are not limited to: Lennox, American Standard, Amana, Everrest, Goodman, Frigidaire, Coleman and Gibson. Brands of related air handling equipment
include Honeywell, Aprilaire, White-Rogers, Broan. Nutone, Fantech, Venmar, Arzel, Hi-Velocity, Vanguard, Wirsbo, Weil McLain, Unico, Heat Link, A.O. Smith, Water Furnace, ClimateMaster, Geo-Excel, Command Aire, Friedrich, LG, Mitsubishi, Sanyo, Hart &
Cooley, Munchkin, Superstor Ultra, Lochinvar and Knight HVAC equipment.
 HVAC Employment: U.S. Department of Labor website describes HVAC jobs and the employment outlook for HVAC technicians.
 HVAC Education, Training Accreditation agencies: Quoting the U.S. DOL HVAC website above:: After completing the programs below, new technicians generally need between 6 months to 2 years of field experience before they are considered proficient. Three accrediting agencies have set academic standards for HVACR programs:
 HVAC Excellence. 1701 Pennsylvania Ave NW,
Washington, DC 20006 Tel: (800) 394-5268. Quoting: HVAC Excellence is a not for profit organization that has been serving the HVACR industry since 1994. It is our goal to improve competency through validation of the technical education process. By setting standards and verifying that they have been met, we inspire the industry to excel. We know that all of the challenges that face our industry are achievable by continuous improvement in the way that we prepare technicians.
 National Center for Construction Education and Research, 3600 NW 43rd Street, Bldg. G, Gainesville, FL 32606, Tel: 888.622.3720, Quoting:
NCCER is a not-for-profit education foundation created to develop industry-driven standardized craft training programs with portable credentials and help address the critical workforce shortage facing the construction industry.
 The Partnership for Air-Conditioning, Heating, and Refrigeration Accreditation, (PAHRA)
2111 Wilson Blvd., Suite 500
Arlington, VA 22201-3001
(703) 524-8800, Quoting: The Partnership for Air-Conditioning, Heating, Refrigeration Accreditation (PAHRA) is an independent, third party organization that is a partnership between heating, ventilation, air-conditioning and refrigeration (HVACR) educators and the HVACR industry that will award accreditation to programs that have met and/or exceeded industry validated standards. This programmatic accreditation program is the only one that is supported by the major industry associations.
Licensure. Heating, air-conditioning, and refrigeration mechanics and installers are required to be licensed by some States and localities. Requirements for licensure vary greatly, but all States or localities that require a license have a test that must be passed. The contents of these tests vary by State or locality, with some requiring extensive knowledge of electrical codes and others focusing more on HVACR-specific knowledge. Completion of an apprenticeship program or 2 to 5 years of experience are also common requirements.
In addition, all technicians who purchase or work with refrigerants must be certified in their proper handling. To become certified to purchase and handle refrigerants, technicians must pass a written examination specific to the type of work in which they specialize. The three possible areas of certification are: Type I—servicing small appliances; Type II—high-pressure refrigerants; and Type III—low-pressure refrigerants. Exams are administered by organizations approved by the U.S. Environmental Protection Agency, such as trade schools, unions, contractor associations, or building groups.
HVAC Training Courses, Schools: HVAC Technician Training Schools [http://technicianschool.net/hvac-technician-training-schools/], lists the following schools offering technical courses may offer specific training programs for potential careers, including HVAC technicians. Among HVAC schools that website lists are
Everest Colleges [http://www.everest.edu],
Florida Career College
7891 Pines Blvd
Hollywood, FL 33024
2299 Vauxhall Road
Union, NJ 07083
NOTE: when considering an HVAC training course or school, check the HVAC education accrediting associations listed above.
 Ratib Bakera is member of Refrigeration Service Engineers Society (RSES), an International
training organization for the HVACR industry provides educational and certification programs to HVACR professionals of all experience levels. www.rses.org provides information on the organization and its training materials. Independent testing and certification of HVAC technicians is provided by North American Technician Excellence - NATE - see www.natex.org.
NATE is supported by ASHRAE, the US EPA, and a host of other trade and professional associations.
 Singer brand HVAC equipment brand history: Singer was bought by & became the climate control unit of Dallas-based Snyder General Corp. (founded by a former Singer HVAC manager) in 1982. The name Singer was dropped in 1984. In 1984 Snyder General operations included Arcoaire, Comfortmaker, and McQuay. In 1991 Snyder General sold Arcoaire & Comfortmaker to Inter-City Products. In 1994 Snyder General was acquired by Hong Leong Group Malaysia. Snyder General is at 2001 Ross Avenue Dallas, TX 75201.
 Lennox air conditioning and heat pump owners manuals for air conditioners, air handlers, furnaces, heat pumps, indoor air quality systems, packaged units, water heaters, zone controls and other controls such as thermostats, are provided by Lennox at http://www.lennox.com/support/manuals.asp
 Air Diffusion Council, 1901 N. Roselle Road, Suite 800, Schaumburg, Illinois 60195, Tel: (847) 706-6750, Fax: (847) 706-6751 - email@example.com - www.flexibleduct.org/ - "The ADC has produced the 4th Edition of the Flexible Duct Performance & Installation Standards (a 28-page manual) for use and reference by designers, architects, engineers, contractors, installers and users for evaluating, selecting, specifying and properly installing flexible duct in heating and air conditioning systems.
Features covered in depth include: descriptions of typical styles, characteristics and requirements, testing, listing, reporting, certifying, packaging and product marking.
Guidelines for proper installation are treated and illustrated in depth, featuring connections, splices and proper support methods for flexible duct. A single and uniform method of making end connections and splices is graphically presented for both non-metallic and metallic with plain ends."
The printed manual is available in English only. Downloadable PDF is available in English and Spanish.
 Engineering toolbox properties of water - http://www.engineeringtoolbox.com/water-thermal-properties-d_162.html and email: firstname.lastname@example.org web search 09/16/2010
 Owens Corning Duct Solutions - www.owenscorning.com/ductsolutions/ - provides current HVAC ductwork and duct insulating product descriptions and a dealer locator. Owens Corning Insulating Systems, LLC, One Owens Corning Parkway, Toledo, OH 43659 1-800-GET-PINK™
 "Flexible Duct Media Fiberglas™ Insulation, Product Data Sheet", Owens Corning - see owenscorning.com/quietzone/pdfs/QZFlexible_DataSheet.pdf "Owens Corning Flexible Duct Media Insulation is a lightweight, flexible, resilient thermal and acoustical insulation made of
inorganic glass fibers bonded with a thermosetting resin."
"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]
 FlowKinetics LLC, 528 Helena Street
Bryan, Texas 77801 USA, Tel: (979) 680-0659, Email: email@example.com, Website: www.flowkinetics.com, "FKS 1DP-PBM Multi-Function Meter
Pressure, Velocity & Flow
User’s Manual", web search 07/16/2012, original source: http://www.flowkinetics.com/FKS_1DP_PBM_Manual.pdf [copy on file] and "FKT Series Flow Measurement And
Pressure Acquisition System
User's Manual" http://www.flowkinetics.com/FKTSeriesManual.pdf [copy on file]
 Histoire de l'Académie royale des sciences avec les mémoires de mathématique et de physique tirés des registres de cette Académie: 363–376. Retrieved 2009-06-19.- Pitot Tubes, Henri Pitot (1732)
 Wikipedia provided background information about some topics discussed at this website provided this citation is also found in the same article along with a " retrieved on" date. NOTE: because Wikipedia entries are fluid and can be amended in real time, we cite the retrieval date of Wikipedia citations and we do not assert that the information found there is necessarily authoritative.
"Pressure sensor", retrieved 7/16/2012
 "GE Zoneline® Owners Manual and Installation Instructions, Heat/Cool Model 2900, Heat Pump Model 3900", General Electric Corporation, [copy on file].
 "GE Zoneline® Owners Manual and Installation Instructions, Heat Pump Model 5800", General Electric Corporation, [copy on file].
 N Lu, YL Xie, Z Huang, "Air Conditioner Compressor Performance Model", U.S. Department of Energy, August 2008, [copy on file as PNNL-17796.pdf] Available to the public from the National Technical Information Service,
U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161
ph: (800) 553-6847, fax: (703) 605-6900
online ordering: http://www.ntis.gov/ordering.htm
 Yinger R, R Bravo, and D Martinez. 2006 Air Conditioner Stalling Effects Study/Air Conditioner Testing
Procedures. Southern California Edison, Rosemead, California
 Bravo, R, R Yinger, and L Gaillac. 2006. Conditioner Stalling Unit Level Solutions Test Report. Southern
California Edison, Rosemead, California.
 Lu N, B Yang and Z Huang. 2008a. Evaluation of Southern California Edison Air-Conditioner Stalling
Solutions. PNNL-17686, Pacific Northwest National Laboratory, Richland, Washington.
 Danny S. Parker, John R. Sherwin, Bart Hibbs, "Development of High Efficiency Air Conditioner Condenser Fans", ASHRAE Transactions June 2005, [copy on file as FSEC-CR-1674-05.pdf]
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones