Gas-Fired Air Conditioning Equipment

For Residential, Commercial & Industrial Applications



Frequently Asked Questions 

 

Why should I consider gas A/C?

Currently, why is electric cooling used more than gas cooling?

Are there different types of gas cooling systems?  If so, what are they?

How much does gas cooling cost?

Are there incentives or special rates that are applicable when using gas cooling?

Is there gas cooling equipment available that would suit my needs?

What are “ideal” applications for a large gas chiller system?

Is gas cooling only applicable to large cooling system applications?

Does it make sense to have both electric and gas cooling?

Where do I go for more help on gas cooling?

 

1.       Why should I consider gas A/C?

Some of the key reasons for using gas cooling are as follows:

         Lower operating costs as compared to electric cooling

         A hedge against the uncertainties of electric industry restructuring

         Non-ozone depleting chlorine-free cooling technology (gas absorption cooling)

         Availability of an abundant fuel that is 95% domestically produced

         Increase in cooling requirements in a facility where the electrical system cannot be easily upgraded

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2.         Currently, why is electric cooling used more than gas cooling?

In the United States, most cooling needs in the 1930s and 1940s were provided by gas.  By the 1960s, electric chillers began making inroads into the cooling market due to lower cost equipment, low electric rates, and higher efficiency machines.  In the 1970s, the use of gas was restricted and electric cooling use continued to increase.  By 1990, only 5% of all air conditioning in the United States was provided by gas.  However, during the 1980s in Japan, efforts (backed by the Japanese government) were being made to accelerate the development of gas cooling.  By 1991, nearly 30% of Japan’s air conditioning was provided by gas chillers.

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3.         Are there different types of gas cooling systems?  If so, what are they?

Yes, there are three basic types of gas cooling systems; absorption, engine-driven and desiccant.   In Southern California, the most popular systems are double-effect absorption (either direct-fired or steam) and engine-driven gas cooling units.  Absorption cooling systems are similar to vapor compression or mechanical systems in that they utilize a cycle of evaporation and condensation of a fluid or refrigerant to produce cooling.   However, absorption cooling differs from the vapor compression cycle by using heat as a thermochemical “compressor” rather than a mechanically-driven compressor.  The source of heat can be from a direct-fired gas burner, from steam or from hot water.   On the other hand, engine-driven gas cooling systems utilize a vapor compression cycle similar to an electric chiller.  The primary difference is that the compressor (reciprocating, screw, or centrifugal) is driven by a high-efficiency natural gas engine rather than an electric motor.

 

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4.       How much does gas cooling cost?

The operating cost (for fuel and maintenance) of a gas cooling system can be as much as 25% to 50% less than an electric system.  However, the first cost of gas cooling equipment is generally higher than electric equipment.  Both the operating costs and the equipment costs are project and site specific.  Therefore, the economics of gas cooling require a life cycle cost analysis, or at minimum, a simple payback analysis to best estimate the actual economics of your facility. 

 

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5.      Are there incentives or special rates that are applicable when using gas cooling?

Yes and No.   Some gas companies offer special incentives for the installation of certain gas A/C systems.   In some cases, special rates are also available for residential customers. 

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6.      Is there gas cooling equipment available that would suit my needs?

         Yes.   Absorption equipment is available from all of the major manufacturers of A/C equipment, Carrier, Trane, York, McQuay, and Dunham-Bush as well as Yazaki, Broad, and Robur, Cention, Energen, Energy Concepts and Thermax.  Engine-driven equipment is available from York, Tecogen, Trane and Alturdyne.  Desiccant equipment is available from AIL Research, Inc., Bry-Air, Concepts and Designs, Drykor, Kathabar Systems Division, Munters Corporation, NovelAire, Seasons 4 and SEMCO.  Residential equipment is available from Ambian, Cooltec, Robur and Novelaire.

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7.       What are “ideal” applications for a large gas chiller system?

The “ideal” application for a large gas cooling installation would be for a project or facility that has many of the following attributes:

         Cooling load of 200 tons or more

         Built-up chilled water system

         In preliminary planning/design phase

         Electric power has high demand charges and/or high on-peak rates

         Majority of the cooling load is during periods of peak electric rates

         Higher emphasis on life-cycle cost than first cost

As noted above, the economics of a project are site specific and do need to be evaluated accordingly

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8.       Is gas cooling only applicable to large cooling system applications?

No.  Unitary or packaged gas cooling is available in both direct expansion (DX) as well as chilled water systems.  Equipment range in size from 3 tons to 500 tons and larger.  This equipment is suitable to most residential and light commercial/industrial applications.

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9.       Does it make sense to have both electric and gas cooling?

         In many cases, the optimal cooling system would incorporate both electric and gas chillers.   In a “hybrid” plant, the gas chillers may be used for the “base load” and the electric chillers would be used only during the peak cooling periods.  In general, this is a more economic and more reliable solution than a thermal energy storage system.   In addition, the ability to have “dual” fuels for your plant may give you added reliability and a “hedge” against future fuel prices in a more unstable restructured energy environment.

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10.      Where do I go for more help on gas cooling? 

         Contact your Gas Company Account Executive or representative who will assist you in evaluating your facility or project to determine if gas cooling makes sense for you. 


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