A Cool Change

R407C is better for the environment and Thermo King's preferred R22 replacement. Shouldn't it be yours?

The Montreal Protocol. ODP. CFCs. HCFCs. Government mandates. EPA rulings. All of these have had a great impact on our industry in the past ten years. We've had to change the way we do things. We've had to change our products and procedures. And that's why Thermo King has introduced HFC-407C (R407C) as the HCFC-22 (R22) replacement for HVAC systems.

"Refrigerant transitions are not new to us," explained Steve Johnson, Thermo King, North America Division bus product marketing manager. "We've successfully completed other refrigerant transitions over the past 15 years.

We've worked closely with leading refrigerant manufacturers and depended on aggressive testing and development programs with each transition. And this one is no different."

Why the change?

The Montreal Protocol of 1987 determined that the most widely used refrigerant in automobile air conditioning, CFC-12 (R12), had to go. It was damaging the ozone. HFC-134A (R134A) became the replacement in that application. Because R22 was less damaging to the atmosphere, it was not scheduled for phase out as quickly. However, current EPA rulings have mandated that no new equipment can be manufactured in North America using R22 after January 1, 2010. And it's already banned for use in bus air conditioning in most European countries. The only thing missing in bus air conditioning was a proper replacement. Until now.

Application-specific refrigerants.

Refrigerants are selected for specific applications based on inherent chemical compatibility and required temperature ranges. Equipment is designed accordingly, and when done properly, the most efficient system for that application is achieved. While R134A has been used to replace R22 in some bus air conditioning applications, it's important to note it was not developed with that application in mind. R22 is the most specified refrigerant for large bus air conditioning systems today.

(Thermo King shipments are 80 percent R22 and 20 percent R134A.) And R407C is one of the designated R22 replacements.

Why R407C?

Thermo King began testing the refrigerant in 1994 and has since tested it in most of the large unit and compressor combinations. The first production units have been running in Spain since early 1996. DuPont has noted the use of R407C (Suva® 9000) as a significant breakthrough for that application, because the buses are required to operate in ambients exceeding 104 degrees F while averaging 300,000 kilometers per year. R134A provided the interim solution, but because it has a significantly lower COP (coefficient of performance) than R22, it consumes much more energy for the same performance.

"DuPont SUVA® R407C is gaining rapid acceptance as the current and future replacement for R22 in packaged reciprocating chillers, air conditioning units and some transport air conditioning applications," said John Bray, global business manager, DuPont refrigerants. "For traditional R22 systems and those driving to reduce size and weight, the market prefers R407C over R134A."

Performance comparisons.

When compared directly, R407C matches R22 in performance. In fact, in the same system with no modifications (except a flush and oil change), the two refrigerants display almost identical performance results. When compared directly to R134A, a R407C system can be smaller, have 20 to 35 percent more capacity and will require less energy to provide the same amount of cooling while operating in the same conditions.

While it is possible to build a R134A air conditioning system large enough to meet the requirements of the Houston pull down test, space availability and weight limitations will not permit such systems in a wide variety of applications. The initial pull down is only one of several performance characteristics that must be considered when evaluating the total duty cycle of a typical transit bus. Once the interior of a bus or coach has been cooled to its specified temperature, an air conditioning system may need only one half of the capacity required for pull down to maintain the interior temperature. If a bus is operating in a climate that makes passing the Houston pull down test a requirement, a smaller, lighter and more efficient air conditioning system will provide the end user with better performance while using less energy.

Availability and price.

"In 1998, production of R407C will grow by more than 60 percent over that in 1997, with 15 to 20 percent of the total consumption being in the United States," said DuPont's Bray. "Prices for R407C are roughly $6 per pound wholesale, some 20 percent less than they were one year ago, and we foresee that costs will continue to decrease as demand and volume increase."

The transition period.

Thermo King's goal is to have all Thermo King R22 air conditioning systems R407C compatible by the year 2000. Thermo King is now releasing some R22 air conditioning systems that may be retro-fitted to R407C in the future. A retro-fit will only require oil changing and flushing (akylbenzene to P.O.E.), an expansion valve change and adjustment, and a complete evacuation. (In some instances, the hoses may have to be changed depending on the age and type used.)

Specifications calling for R407C are expected to increase as the industry becomes more comfortable with the new refrigerant and as the phaseout date draws closer. Some of the more environmentally-conscious agencies and others who are already using HFC refrigerants are likely to begin the transition to R407C before the laws make it mandatory.