In fact, company officials contend that teaching comes first, as was demonstrated earlier this year when some 50 area contractors and technicians came to the facility one evening for a quick meal and an extended session on the latest information on refrigerants. It was a variation on a program that the company has been taking to supply houses and trade association meetings for several months.

The basic message from one of the presenters, national sales director Gordon McKinney, was that once upon a time, the HVACR industry had only a few refrigerants to deal with. Now there are many more. In some instances, manufacturers and other equipment specifiers are still feeling their way through the options.

In addition, certain refrigerants may work best in a more limited range of applications than their predecessors. McKinney urged the audience of contractors and technicians to consult with manufacturers on such matters.

He noted that the industry is facing challenges on several fronts. Legislation is phasing out HCFCs, "leaving the industry and consumers searching for solutions." In addition, "Equipment manufacturers are under pressure to drastically increase the SEER rating of their systems to offset the world's growing energy demands."

As the phaseout of HCFCs continues, McKinney projected that the year 2010 will be a pivotal one because of two factors:

1. Use of HCFCs will have to be reduced by 65 percent of a benchmark set in the late 1990s.

2. OEMs no longer will be able to use HCFCs. McKinney expects prices of HCFCs to rapidly go up at that point.

Terminology

He described a "substitute" as "an alternative refrigerant that is used in equipment that has been specifically designed for the refrigerant. They [substitutes] are not suitable as service replacements for systems that are CFC- or HCFC-based." He said R-410A is one such substitute.

"Replacement" was described as "an alternative that is designed for use as service replacements in CFC- and HCFC-based systems and requires a significant amount of retrofit procedure."

"Direct replacement" was said to be "an alternative that is de-signed to use as a service replacement, with little or no additional retrofit requirements."

McKinney noted a number of factors that will influence the decision as to what refrigerants will become long-term choices. For the contractor, the concerns might include practicality or overall ease of use, efficiency in terms of total reduction in energy consumption, versatility (so they can work in a wide range of R-22-based equipment), safety, and/or availability (whether the refrigerant blend is easily manufactured with existing, readily available refrigerants).

Another component of new refrigerants is whether they are azeotropic blends (in which there is no glide factor) or zeotropes (which have a glide factor).

Regarding zeotropes, McKinney said charging must be done in the liquid state. "If charged in vapor, the resulting composition in the system and the cylinder has been compromised."

He added, "With the components changing state over a range of temperatures [glide], the effectiveness of the coil surface is increased. In the context of a leak, fractionation only occurs when liquid and vapor are present together and vapor leaks. Practically speaking, this doesn't occur to the extent that the industry anticipated."

Gordon McKinney talks refrigerants with contractors and technicians from the Indianapolis area.

The New Refrigerants

Discharge pressures are 50 psi higher than R-22, he said. "At evaporator temperatures above 10 degrees F, there is an energy efficiency loss of 5 to 10 percent. At evaporator temperatures below 10 degrees, energy efficiency increases up to 20 percent at -40 degrees, making this a good low temperature refrigerant."

R-404A is similar to 507 except for the addition of 4 percent R-134a to a blend that has 52 percent R-143a and 44 percent R-125. McKinney labeled the refrigerant as a zeotropic blend, meaning it must be charged as a liquid and has some glide. It has, he said, the flooded evaporator potential, a topping off option, and oil change requirements similar to R-507. Its evap temperature is similar to that of 507 as well, he noted.

R-410A is a 50/50 mix of HFCs 32 and 125. It is being marketed as a replacement for systems that used to rely on R-22, although it is not a retrofit refrigerant. "It cannot be used as a service gas on R-22-based systems." OEM's are designing equipment specifically for use with 410A, he said, adding that R-410A has "up to 60 percent higher refrigerating capacity and operating pressures compared with R-22, and requires product-specific service tools and the use of an XH-11 desiccant-type drier."

He did note that R-410A has a low Total Equivalent Warming Impact (TEWI). This, he said, is an important consideration. HFCs are raising eyebrows in some parts of the world because of their Global Warming Potential (GWP). That concern can be mitigated when TEWI is factored in, he said. TEWI, for example, factors in the cost of generating power to run systems. A low TEWI is considered a good thing. McKinney said that could become an issue if efforts are made to regulate some HFCs.

"TEWI is what everybody is going to be looking at when they get to passing some global warming legislation. That's going to happen." He speculated that U.S. governmental bodies could be swayed by actions currently going on in Europe that are creating some uncertainly as to the future of HFCs.

A fourth refrigerant in the new category is R-407C, a blend of R-32, -125, and -134a. It is billed as an R-22 replacement but not in centrifugal/flooded evaporator systems, he said. It is a zeotrope and has glide. "It has similar operating characteristics and capacities compared to R-22 and up to 25-psi higher discharge pressures compared to R-22, as well as lower energy efficiency." It also needs a POE oil and an XH-11 desiccant-type drier.

McKinney then turned his attention to R-417A, an HFC made by his company and several others. It is a blend of 50 percent R-134a, 46.6 percent R-125, and 3.4 percent R-600 (butane).

Like all the other refrigerants he mentioned, R-417A has an A1 safety rating because of the small quantity of R-600, which is used "for oil return in all temperature ranges."

He said 417A has very low TEWI and up to a 10 percent energy reduction compared to R-22. Furthermore, he said, "There is a slight loss in refrigerating capacity compared to R-22. We get beat up a lot [by larger refrigerant manufacturers] over that. But it is not as bad as they say it is."

The selling point, he said, is that it can be used "in both new and existing R-22-based systems with the least amount of system or production line modification. This will expedite the removal of HCFCs from the market."

In addition, he said, the HFC can work with mineral oil. "This means no oil change when servicing existing R-22 systems, therefore reducing the amount of waste oil handling and disposal."

He noted that R-417A works best within a specific framework. For example, it is best used with a system designed for use with R-22 rather than a unit that was originally an R-12 system and later converted to R-22. "If a system has undergone a previous conversion, it is best to contact the refrigerant manufacturer for assistance."

He also said the refrigerant is designed for direct-expansion systems that incorporate cap tubes, thermal expansion valves, or orifice metering devices. Possible use with flooded and liquid overfeed systems should be considered with the assistance of the refrigerant manufacturer. The refrigerant works best "in systems that are in good operational condition prior to conversion, and that provide adequate refrigerating capacity and oil return."

When converting a system from an HCFC to any HFC refrigerant, McKinney urged his audience of contractors and technicians "to thoroughly leak check after the conversion." He cautioned, "Most elastomers swell when exposed to any refrigerant. It is possible that the O-ring will swell a different amount when exposed to an HFC refrigerant that has been put into a system that previously contained R-22."

The Interim Option

James Hale, technical support supervisor at ICOR, noted a deluge of interims, especially those designed to replace CFC-12. "Many of these replacement refrigerants have a limited temperature range and require various degrees of system conversion and ‘fine tuning.'"

Hale urged technicians to make sure they have Environmental Protection Agency (EPA) certification to purchase refrigerants and to make sure refrigerants are on the Significant New Alternative Policy (SNAP) listing of the EPA. Furthermore, techs should make sure the refrigerants have an acceptable Underwriters Laboratory classification.

"The primary ACR industry concerns in regard to alternative refrigerants are toxicity and flammability," he said. "Make sure the refrigerant has received the best safety qualification a refrigerant can receive."

Hale also raised a red flag over the idea of mixing refrigerants. "First of all, it is against EPA Section 612 regulations. Second, you could end up creating a new refrigerant; then what pressure-temperature chart do you follow? Thirdly, no [reclaimer] wants to handle or process mixed refrigerants - it's too expensive."

He also offered advice on sight glass charging. "When a blended refrigerant passes through a sight glass, it will tend to flash inside the larger cavity of the glass. However, it does reintegrate as a blended liquid directly after passing through. This ensures you have a full stream of liquid to the metering device."

A portion of Hale's talk focused on interim refrigerant R-414B, which is manufactured and marketed by ICOR. Hale called it "the most versatile alternative to R-12, -134a, and -500 in high-, medium-, and low-temp" applications.

Publication date: 11/03/2003