This article is about future “Second-Generation”  Evaporative Coolers (also known as Swamp Coolers).  They are called DeVap Coolers because they dehumidify incoming air before the air passes through the Evaporative Cooler.   This product is being worked on (as a prototype) because a  second-generation DeVap Cooler will work in high humidity locations like DFW.  It will operate (in DFW) for about 1/2 the cost of central a/c).

Conventional Evaporative / Swamp Coolers only work in areas with low humidity.  They are ideal for only desert and semi-arid climates.  In order for a swamp cooler to work, the incoming air must have quite low humidity.  If incoming air has high humidity, the evaporation process cannot occur, and the air coming of of the cooler will not be sufficiently cooled.  At 85% relative humidity, a swamp cooler does not cool at all.

Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally we sell and install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Al’s is near your home in Plano, Garland, and Richardson.  We service all homes in southern Denton and Collin Counties with no additional travel charges.

Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience and offer 24/7 Emergency Service.

A (Future) Second-Generation Evaporative / Swamp Cooler

DeVap Cooler That Works In Humid Climates Like DFW

DeVap Coolers Combine: 1. Dehumidifier + 2. Evaporative Cooler Into 1 Unit

NOTE:  DeVap Coolers Are Currently In Prototype.  They Are Not Yet Available For Purchase At The Time This Article Was Written (December 2018).

Why Evaporative / Swamp Coolers Don’t Work In High Humidity Areas Like DFW

Shown: A Conventional Evaporative Cooler — Also Known As A Swamp Cooler

Image Source: Shutterstock

Many of us have seen or heard of an Evaporative Cooler.  They are often referred to as a “Swamp Cooler”.  They work on a very simply principle.  Water runs through a mesh surface inside the cooler, while the cooler’s fan draws air through the wet pad.  Evaporation of the water cools the air as it passes through.  Evaporating water cools the air, just like evaporating sweat cools our skin.  

The Problem With Evaporative Coolers In DFW Is That Our Humidity Is Too High 

Relative Humidity is the air’s ability to hold humidity at the current temperature.  As temperature rises, relative humidity percentage lowers — even though the amount of humidity hasn’t changed.  This is why Weather Reports use “Dew Point”.  Dew Point is humidity measurement that doesn’t change with air temperature.

Ideal indoor air relative humidity is up to 50%. *  DFW summer average relative humidity level = 60%.  In July, DFW’s relative humidity is up to 80%.   At 85% humidity, an evaporative cooler cannot cool at all (because the humidity is too high).  To resolve this problem in humid areas like DFW, a Second-Generation Evaporative Cooler has been built (a prototype at this time).

DeVap Coolers:

• Dehumidify the incoming air.
• Then pass the dehimidified air though a traditional evaporative cooler.
• This allows DeVaporative coolers to work in humid climates.
• It also dramatically increases their ability to cool.
• Devap Coolers are far less expensive to operate than conventional a/c (details below).

A DeVap Cooler can dehumidify air to below 20% relative humidity before the air enters the evaporative cooler. ***  The humidity added during the evaporative cooling will not raise the humidity of output air above 50%.   With 20% humidity air entering the cooler, output air at 74 degrees on a 95-degree day.

*   The Mayo Clinic recommends a humidity level between 30-50% inside the home.

** https://www.sylvane.com/indoor-swamp-cooler-faq.html

*** https://www.nrel.gov/docs/fy13osti/54087.pdf

See A Photo Of The Prototype DeVaporative Cooler Below

Click On The Arrow In The Center Of The Image For A Short YouTube Video Describing DeVap Coolers

States Where Conventional Swamp Coolers Work Well

Roughly the western third of the U.S. has a climate dry enough for traditional evaporative coolers.

Click Here For A U.S. Map Showing Typical Humidity Levels: U.S. Map Showing Summer Humidity Levels

These specific areas have a suitable climate for Evaporative Coolers:

• Washington
• Oregon
• California (northern 2/3)
• Montana
• Idaho
• Wyoming
• Utah
• Colorado
• Nevada
• Arizona  (northern 2/3)
• New Mexico (western 2/3)

Swamp Coolers will only work in Texas roughly west of the eastern border of the panhandle.    This is where Texas’ climate changes from Humid Sub-Tropical to Semiarid.  Even there Swamp Coolers won’t work great because the air is still too humid. 

Las Vegas Has The Right Humidity Level For Evaporative Coolers. 

So Why Are Evaporative Coolers Not Used A Lot There?

• Daily Average Humidity = 21%
• In July, Las Vegas’ relative humidity = 15-26%
• Las Vegas Has An Ideal Climate (for humidity) For An Evaporative Cooler. 

• At 90 degrees, the cooler can lower the temp of its output air to 70 degrees (with average daily humidity level = 21%).
• Las Vegas’ July average high temperature = 105 degrees.  A conventional Evaporative Cooler can only cool to 81 degrees (at 21% humidity).
• A DeVap Cooler could provide incoming air at 5% humidity, then it could cool to 74.  This is possible because the air in Las Vegas is already quite dry.

** Source: https://ask.extension.org/questions/199796

A (Future) Second-Generation Evaporative / Swamp Cooler — DeVap

DeVAP stands for “DEsiccant Enhanced Evaporative.”  

A DeVap System Includes: A Dehumidifier + Evaporative Cooler (swamp cooler)  

Image Source: Youtube Embedded Video

The A/C compressor is what uses tremendous amounts of electricity.  An older,  SEER-10,  3-ton A/C (size for a 2,000 square foot home in DFW) uses 3,600 watts per hour.  A SEER-14 A/C (today’s minimum SEER in DFW) uses 2,575 watts. **

** Note: Divide the BTU’s by the SEER to determine how many watts a central a/c uses.

As Compared To Conventional A/C:

• DEVAP does not use a compressor or refrigerants.  It uses salt-water to remove humidity from the incoming air.

• A/C passes humidity air over the cooling-coil (inside the furnace).  Because the coil is so cold, much of the humidity within the air condenses on the cooling coil.

• DeVap Coolers uses a salt water desiccant to remove humidity.

• Then, A DeVap Cooler uses heat (provided by natural gas) to evaporate the water out of the desiccant.  This step is completed inside a “regenerator”.

• DeVap Coolers only use energy to dehumidify (with natural gas) & distribute the air (with electricity).

• Cooling of the air is done by Evaporative Cooling, a Natural Cooling Process.   It’s a natural cooling process, as when we sweat.

• Devap Systems don’t constantly use water like Evaporative / Swamp Coolers.  The water removed during the dehumidifying process is then reused in the Evaporative Cooling.

Click Below For A Technical Explanation Of How Desiccant-Enhanced Evaporative Coolers Work

Technical Explanation of Desiccant Enhanced Evaporative Coolers

We Describe Desicccant Devaporative Coolers In Laymen’s Terms Below 

Shown: Silica Gel Is A Desiccant (Removes & Holds Humidity)

Image Source: Shutterstock

“Desiccant” Is The Technical Name For Any Substance That Removes & Holds Moisture

You often see Silica Packets inside packaging of products. Silica is a desiccant.  If a packet is included, it’s there to eliminate any moisture that could affect the product.

The premise of Second Generation – “DeVap Coolers” is adding equipment to dehumidify the air before it enters the Evaporative Cooler.  The dehumidifying process is provided by a Liquid Dessicant (in this case, highly concentrated salt-water).  The drier the air entering the evaporative cooler is, the lower temperature it can cool to, and without excess humidity in the output air.  DeVap coolers can perform well in ares with high humidity.

Natural Gas is used to dry the Dessicant (salt water) after it has removed the humidity from the incoming air.   It can also be provided with solar energy.  For this reason, the amount of electricity consumed by a DeVap Cooler is up to 90% less than conventional a/c.   Natural gas prices in DFW are quite reasonable, creating substantially lower operating-costs for a DeVap Cooler as compared to conventional air conditioning.

DeVap Cooler Operating Costs — And Compared TO Central A/C

Evaporative Cooling Is Very Energy-Efficient Because It Uses A Natural Cooling Process (evaporation).

It’s the same as when we sweat.  Our skin becomes cooler because the sweat is evaporating.

• DeVAP units consume up to 90% less energy than conventional A/C.  Actual savings depends on the humidity level in the area where the DeVap Cooler is located.

• Compared to an 18 SEER A/C — tests determined a DeVap system would achieve a 50% operating costs savings in Houston (74% average summer humidity).

• Based on Houston performance, a 55% savings in DFW could be expected (60% average summer humidity) **

• A DeVap System also uses natural gas to dehumidify the air.   Once the salt-water desiccant has removed the humidity, it must be heated to remove the moisture from it.

• A 3-ton DEVap A/C uses a 30,000 BTU boiler as its Desiccant Regenerator (the dehumidifier).  As compared, a 50-gal. water heater = 36,000 BTU.

• A term of natural gas provides 105,000 BTU of heat.  Running constantly, the Desiccant Regenerator uses 30,000 BTU per hour, or 720,000 BTU’s of natural gas per day.  It takes 7 therms of natural gas per day (if running continuously).  A therm costs 16.5 cents X 7 therms per day = $1.15 Daily gas cost (if it ran continuously).

• The blower fan motor uses 500 watts per hour.  Running for 24 hours, it would use 12,000 or 12 kWh.   Daily electricity cost = $1.55  (if it ran continuously).

Total Daily DeVap Cooler Operating Costs = $2.75 (if running constantly)

Compared To Central A/C:

• A SEER-14, 36,000 BTU Central A/C uses 2,575 watts per hour.  If running continuously it uses 62,000 watts, or 62 kWh (kilowatt hours).

1 kWh costs 12.8 cents X 62 kWh = $7.95

Total Daily Central A/C Operating Costs = $7.95 (if running constantly)

Notes:

• The more humid outdoor air is, the more gas is needed to dehumidify incoming air in a DeVap Cooler.  This increases operating costs.  Our numbers shown are for the dehumidifier / regenerator running continuously.

• If the humidity level of incoming drops below 40%, the dehumidifier can be turned off.  With dehumidifier off, no natural gas is consumed — reducing operating costs.

** https://psmag.com/environment/air-conditioning-using-90-percent-less-power-20071

*** https://www.nyseg.com/UsageAndSafety/usingenergywisely/homeenergyuse/NaturalGasAppliances.html

 How DeVap HVAC Works

Click Here To See A Diagram Of A DeVap Cooler: DeVap Cooler Diagram

STEPS OF HOW A DeVAP COOLER WORKS

• All Return Air (from the building) + some outside, fresh air enters the dehumidifer (yellow arrow in diagram provided by link just above).
• Humidity is removed by the salt-water Desiccant.  Heat is then used to dry the desiccant.   The removed humidity + the heat are vented outdoors (red arrow).
• The Dehumidified Air enters the Evaporative Cooler.
• The Air is cooled using evaporation.
• Cooled, dehumidified air enters the building (blue arrow).

A DeVAP SYSTEM COMBINES:

Dehumidification:   The Salt-Water Desiccants’ Ability To Remove Humidity (dry out) from the Incoming Air

Cooling: An Evaporative Cooler Cools The Dehumidified Incoming Air (from the dehumidifier).

The Combination (of Dehumidifier + Evaporative / Swamp Cooler)  Allows A DeVap Cooler To Work In Humid Areas (like DFW).

Differences Between DeVap Cooler & Central A/C System

• DEVap Cooler does not have a large outdoor condenser unit.  It uses a much smaller “Desiccant Regenerator” / dehumidifier (powered by natural gas).  The regenerator can be placed inside or outdoors.
• Conventional A/C utilizes complicated process where refrigerant removes heat from the air as it passes through a cooling-coil (inside the furnace, or above furnace within the ductwork)
• Conventional A/C then moves the refrigerant (laden with heat) outdoors — where the heat is removed from the refrigerant as it passes through a condensing-coil in the outside unit.

• Moving refrigerant with a compressor consumes a lot of electricity.
• DeVap cooler does not have a compressor.  It uses electricity to pump the water and distribute the air.
• DeVap uses salt-water desiccant to dehumidify.  Heat is then added to dry the desiccant.  The heat is generated burning Natural Gas.
• Once heat is used to dry the salt-water desiccant, the heat and humidity are vented outside.

• The DeVap System does not require a chemical refrigerant.  It uses salt-water as its refrigerant.
• The American Society of Heating, Refrigerating & Air-Conditioning Engineers (ASHRAE) recognizes water as “Refrigerant R-718”.

• Newer residential air conditioners use R410A refrigerant.
• R410A refrigerant won’t damage the Ozone Layer.
• But, R410A is a strong contributor to global warming (when released into the air by a refrigerant-leak).

• “Greenhouse-Gases” trap heat by absorbing the sun’s heat.
• Global warming potential (GWP) is a measure of how much heat any greenhouse-gas traps in the atmosphere.
• R410A refrigerant’s global warming potential = 2000.
• R-22 / Freon’s global warming potential = 1810.  It’s a little lower, but damages the ozone layer.

On A Side Note –Salt Water May Soon Be Used To Cool The Earth

Sea-salt Climate Engineering may become a way to slow global warming.  This is how it works: Specially designed, unmanned boats spray the ocean’s salt-water into the air. The water evaporates & leaves behind sea-salt particles.  The sea-salt particles lift into the clouds, increasing the clouds’ reflecting-ability.  ****

While yet in prototype, sea-salt engineering may be used in oceans to keep the earth’s top-of-atmosphere “Radiative-Forcing” at the year 2020 level..

“Radiative-Forcing” is the difference between the amount of the sun’s heat absorbed by the Earth and the amount of the sun’s heat radiated back into space.  The more heat is radiated, the cooler the earth would become.  “Greenhouse-Gases” absorb heat made by the sun.

**** https://www.scientificamerican.com/article/salt-spray-may-prove-most-feasible-geoengineering/

SUMMARY:

At present, DeVap Coolers are still in prototype.   In time, they will become available, and will create large operating-costs savings when compared to conventional air conditioning.  Actual savings is determined by the humidity level in the air where the cooler is located.

DeVap Cooling uses a conventional Evaporative Cooler (as known as a swamp cooler).  They cool the air by passing air through a water filled mesh.  As the air passes through the mesh, evaporating water cools the air — just like evaporating sweat cools our skin.   Conventional swamp coolers are only useful in areas with low humidity such as the western 1/3 of the U.S.

DeVap Coolers include a dehumidifier.  The air is dehumidified first — then passed through the evaporative cooler.  The lower the humidity of the incoming air, the better an Evaporative Cooler can cool.  A DeVap Cooler is able to perform well in climates with high humidity.  The higher the humidity, the harder a DeVap system must work to dehumidify the incoming air.  While high humidity increases operating costs,  DeVap coolers still operate much cheaper than conventional a/c.   As presented in this article, in DFW a DeVap Cooler will cool for a around 1/2 the cost of regular a/c.

Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally we sell and install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Al’s is near your home in Allen, Frisco, and McKinney.  We service all homes in southern Denton and Collin Counties with no additional travel charges.

Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience and offer 24/7 Emergency Service.