Types and advantages of Evaporative Coolers

Evaporative Cooler Selection Tips

Want the chilling comfort of an evaporative cooler for the space of choice but are not sure of the type, capacity, brand, price, and specifications that suit your purpose? Read on to find the answers to all your questions on price, technical specifications, and the best coolers on the market.
Evaporative (swamp) coolers and their ducts are frequent sights to spot on the rooftops. An evaporative cooler supplies a cool flow of air with the help of the evaporation of a thin layer of water sprayed over excelsior or cellulose pads.

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Advantages of an Evaporative Cooler

Overall, evaporative cooling is a common, optimal method of supplying cool air to space, provided that the ambient relative humidity is under 40%.
Generally speaking, evaporative coolers are recommended for hot and arid climates. This method of cooling humidifies the atmosphere—by diffusing moisture into space—and prevents woodwork from cracking and reduces the generation of static electricity, in addition to supplying the space with cool air.
Therefore, one may conclude that air conditioners are suitable for hot and humid climates whereas evaporative coolers are the best fit for arid climates.

The most important reasons for selecting an evaporative cooler are:

Lower price
Lower power consumption
Easy installation and start-up
Low operating and maintenance costs

evaporative coolers

Types of Evaporative Coolers

Portable evaporative cooler: as the name suggests, this cooler can be moved and displaced. The water tank can be either filled manually or connected to water mains by a hose.
Fixed evaporative cooler: this is the most common type of evaporative cooler and is often installed outdoors over the rooftop, on the balcony, or in the yard due to its large dimensions and uses ducting to supply cool air to the rooms.

Based on their cooling mechanism, fixed evaporative coolers can be divided into two general groups, namely evaporative coolers with typical excelsior pads and those with cellulose pads.
In a typical evaporative cooler, water is sprayed over excelsior pads, cooling the air as it passes through. However, the excelsior pads lose their integrity in less than one month and become partially depleted, thus reducing the cooling efficiency.

energy evaporative cooler

Meanwhile, an evaporative cooler integrating cellulose pads is capable of supplying a better and more uniform flow of air thanks to the superior volume integrity of cellulose.
Replacing excelsior with cellulose pads in evaporative coolers provides better cooling (2–3 °C cooler than a cooler with excelsior pads) thanks to the higher water absorption and the uniformly-stacked layers of cellulose, better distribution of water over the pad, and—consequently—more effective contact area between the passing air and the wet cellulose pad surface. The cellulose pad is also more effective in filtering particulates and bacterial contamination from the air.
Evaporative coolers with axial fans: This type of evaporative cooler—that is window-mounted—can only supply air in the horizontal direction and does not use ducts. Centrifugal fans are generally installed in fixed evaporative coolers to overcome the pressure drop resulting from the air passing through ducts. However, evaporative cooler fans with axial fans (that cost as low as half the typical evaporative coolers) are the best choice for cases where an evaporative cooler is used without ducting (do not forget that this type of evaporative cooler also needs to be installed outdoors to receive a supply of fresh air).
The portable type of evaporative cooler with axial fans must be similarly placed with its posterior exposed to fresh outdoor air. Therefore, this type of cooler (window-mounted) is used in cases where the cool air will be supplied to the room directly and not through ducts.

Further, evaporative coolers can be also divided into two groups based on their outlet placement.
Evaporative coolers that have their air supply outlet located on the side (side-draft) and those with outlets on the top (up-draft).
Up-Draft Evaporative Coolers: This type of evaporative cooler is fit for installation on the balcony and has an air intake on its four sides. The up-draft configuration facilitates ducting if the cooler is installed on the balcony.
It is important to note about starting up evaporative coolers that, given the high rate of fatal electrocution during maintenance, make sure to have the equipment switched off in advance or get professional help.
It must also be noted that up-draft evaporative coolers are available with both excelsior and cellulose pads.
Under the Evaporative Coolers category at DamaTajhiz.com—the first (from 2005) and largest online retailer for heating and cooling equipment in the Middle East (according to Alexa. com)—you can easily find a product that fits your requirements at the best price (best price guarantee) by browsing through the comprehensive descriptions provided, assured to receive original services and warranties.

absal evaporative cooler

How to Select the Capacity

The required capacity of evaporative coolers with either excelsior or cellulose pads differs depending on the floor area and whether the apartment is located on the top floor just under the roof or in the middle of the building. Although, it must be noted that, being exposed to direct sunlight from the top in the summer, apartments located at the top-most floor require a higher cooling capacity and even auxiliary mini-splits in some cases (for further information visit buying guides for each evaporative cooler model at DamaTajhiz.com).
The capacity of evaporative coolers must be selected in proportion to the floor area and the effective area of the building and the regional climate—from the standpoint of temperature and humidity.
Using a cooler of higher capacity than the size and capacity of the implemented ducts or the output capacity of the vents leads to the annoying sound of flowing air during the operation.

Consider Safety Measures When Starting Up an Evaporative Cooler

Electrocution is a common hazard during the maintenance and start-up of evaporative coolers exposing the residents and technicians to the risk of injury. Remember that the inner surfaces of this type of cooler are wet, which helps intensify electrocution.
The cooler features a metal cooling box and its wiring is difficult to follow. It is, therefore, best to leave any repair or maintenance to professionals and never take on repair jobs alone.
If you have moved in recently, remember to check the cooling box with a test light for electricity before changing the cooling pads. Nevertheless, evaporative coolers must be equipped with life-safety systems that automatically disrupt the power to prevent electric shocks.
However, in any case, if you are planning to repair the equipment yourself, make sure it is switched off before any attempt. It is best to go to the cooler with a family member or inform them about it.

Note the Following when Switching an Evaporative Cooler On

When switching an evaporative cooler on, it is necessary to crack a window in the kitchen or a room and turn on the kitchen ventilation fan to allow the input air out.
Furthermore, cooler vents should not be installed in the kitchen to prevent potential hazards, such as blowing off the stove.

Installing the Evaporative Cooler and Changing Excelsior or Cellulose Pads

If the evaporative cooler is installed on the roof, please check the dimensions provided in the specification tables and make sure it fits through the roof access door.
Evaporative coolers are often installed on a #3 or #4 structural angle base, depending on the required height (the base is not included).
It is also important to ensure the cooling box is perfectly balanced after installation to guarantee a uniform distribution of water over the cooling pads that leaves no part of the pads dry to reduce the cooling efficiency.
Furthermore, if unbalanced, the vibration of the centrifugal fan will make noises besides damaging the bearing and the cooling box.
Every year, before starting up the evaporative cooler, excelsior pads must be changed and equipment checked by a professional. Further, the bottom and internal surfaces of the cooler must be cleaned to remove dust and bacterial and fungal contamination, as the flow of air can deliver them to the indoor space from the cooling box, which is a damp, dark atmosphere that promotes bacterial growth.
This is particularly problematic in polluted cities such as Tehran where the air is contaminated by more particulates. Therefore, never postpone changing the excelsior or cellulose cooling pads.
Excelsior pads must be changed at least once a year (at the start of the hot season), but twice a year in polluted cities such as Tehran (once in June and once in mid-July).
On the other hand, cellulose cooling pads must be changed every 3–5 years (depending on the soluble salts in the water and the regional air quality).
As it was discussed earlier, using a cellulose cooling pad instead of excelsior offers several advantages such as better cooling and filtering out particulates. However, the use of glue and resins for fabricating the pads necessitates draining the water collected in the basin several times for deodorization.
Considering the cooling mechanism in evaporative coolers, it is necessary to install the equipment in a location exposed to fresh air to prevent over-humidification.
Further, given that evaporative coolers are often used in dry climates and that a single unit can use up to 300–400 liters of water in a day, it is best to install a thermostat on the switch to control the function and avoid unnecessary water and power consumption (the exact water and power consumption depend on the ambient air temperature, relative humidity, and the operating duration in addition to the dimensions and capacity of the cooler).
It must be noted that covering the cooling box at the end of the summer can reduce energy consumption by limiting heat dissipation through the vents and ducts, as well as preventing the infiltration of rainwater into the basin and rusting in autumn and winter. It can also block dust—which will be blown into space by the stream of air when the equipment starts up—from entering the box and settling on the fins of the centrifugal fan.

The Importance of Correct Ducting for Evaporative Coolers

The aeration and cooling of an evaporative cooler depend on the fulfillment of the principles of correct ducting. Further, pay attention to the descriptions provided in the buying guide for the different cooler models.
It is necessary that the ducts are implemented according to the facility's engineering calculations and based on ductulator tables complying with ducting standards (in terms of duct dimensions, the volume of passing air, branching, and curves). You can visit the Ducts and Vents section at DamaTajhiz.com for additional information and important tips.
To improve the cooling efficiency of evaporative coolers it is strictly recommended not to install the evaporative cooler and its ducts exposed to direct sunlight. Therefore, you can block solar irradiations by covering the cooling box with shades and insulating the ducts (according to the Iranian National Building Code, in case the duct is exposed to direct sunlight and is over 2 m long, it must be insulated).
Additional emphasis: the dimensions of the ducts must comply with ductulator tables and engineering calculations.

The structure of an evaporative cooler is generally divided into mechanical and electrical parts

The mechanical part of the cooler is composed of the cooling box, water pipes, internal and external ducts, bearing, blower pulley, v-belt, and the water distribution system.
evaporative cooler structure
The electrical part of the evaporative cooler comprises the water pump, two-stage electric motor, fan, electrical box, start capacitor, power factor correction capacitor, four-string cable, and the special switch.

You can also read the article THE DIFFERENCE BETWEEN A EVAPORATIVE COOLER AND A SPLIT AC UNIT for more information.

Final speech

The specialized collection (Damatajhiz) (the first and most reliable authority in the country in the field of building facilities equipment and all air conditioning devices), offers you all kinds of sand filters and hundreds of other products, guaranteeing the originality of the product, valid warranty, and reasonable price. In addition, if you have any questions about choosing and comparing the brands of this product, you can get free advice from the heating equipment experts.

In Iran, the first and most famous specialized group in the field of building installation equipment, air conditioners, and all equipment for swimming pools, saunas, and jacuzzis since 2004, DamaTajhiz is a specialized group. Refer to the time of this group. For more information, you can get advice from the experts of DamaTajhiz Engineering and Production Company by calling 021-88822550.

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