Pressures for R-410A unitary systems are 60% to 70% higher than those for R-22 systems. (Photo courtesy of Carrier Corp.)
When unitary heat pumps and air conditioners using R-410A were introduced to hvac contractors, many were skeptical. They had been working with R-22 systems for so long, the change seemed unreal. Then there were the new refrigerant’s higher operating pressures, which alarmed many.

Even as recently as last year, the system manufacturers themselves, though pleased with the new refrigerant’s efficiencies, were hesitant to comment on how contractors were adapting. This year they are speaking out, and the news is good. Training is helping contractors feel confident about products using this relatively new refrigerant and is keeping the number of returns to a minimum.

One of the main indicators comes from compressor manufacturers, whose products are returned under warranty for problems that more often relate to causes such as poor installations and/or poor diagnostics, rather than an actual problem with the compressor.

The number of oem’s offering 410A systems and the number of units already in the field has reached “critical mass,” said John Schneider, residential market manager for Copeland Corp., Sidney, OH. “With regulations [for R-22 phaseouts] coming, these trends will continue.

“I’ve thought for a long time that 2002 would be a telling year,” said Schneider. “Copeland has sold over half a million 410A scroll compressors to the unitary market, and is quickly heading to that one million mark.”

In order to install and service the increasing number of 410A unitary air conditioners and heat pumps entering the market, large numbers of contractors have sought training from their equipment manufacturers. Some of what they cover is specific to the 410A systems, but much of it is just good service practice that should be applied to any unitary system.


The results of the training are being reflected in hard numbers, such as reduced in-warranty compressor returns — not only a reduction of R-410A compressors vs. comparable R-22 compressors, but a reduction in R-22 compressor returns over previous years, said Schneider.

In his position, Schneider said he has been “looking for what proof there is that R-410A is the right choice long term. I look at parameters like the number of oem’s with R-410A units, the number of years the oldest of them have been installed, and the number of in-warranty compressor returns.”

According to Schneider, the oldest 410A units have been in the field about six years, and most all unitary manufacturers now offer 410A a/c and heat pump models. In general, R-410A scroll in-warranty returns have been down 40% from comparable R-22 compressor in-warranty returns, he said.

“The in-warranty returns for R-22 scrolls [from unitary equipment] have also dropped,” he said.

One conclusion is that training is having a positive crossover effect. Schneider believes the quality of training, particularly the training being provided by manufacturers of the unitary air conditioners and heat pumps, has had the greatest impact. He also noted that contractors have a desire to become well acquainted with the newer refrigerant.

The designated color for R-410A is rose.


Safety, of course, is an essential part of the training. The refrigerant’s higher operating pressures (60% to 70% higher than R-22) make it mandatory that contractors and techs use new gauges designed for 410A. At least one manufacturer, Amana, redesigned its equipment gauge fittings so that old gauge sets cannot be used at all. When contractors receive training from this manufacturer, they receive new gauge sets that work with the new fittings.

Dan Rasmussen, an American Standard product support leader based in Tyler, TX, conducts a 6-hr training program through the company’s distributors. As a result, he has a busy travel schedule.

“As a company, we ask that all distributors provide [R-410A] training to their dealers,” he said.

When Rasmussen talks about safety, he discusses new tools, gauges, valves, and recovery equipment able to handle higher pressures.

“The biggest safety concerns are from the higher pressures. If somebody was careless and used their old gauges, they’ll blow apart,” he said, noting this could lead to freeze-burns and injury from flying metal (shrapnel). “R-410A will burn you quicker [than R-22]. It’s so important that we get contractors up to speed.”

Essentially, the whole program is about safety, “first and foremost,” he said. For instance, in refrigerant handling:

  • When working, use gloves and safety glasses with a visor.

  • Use proper storage in the service vehicle (standing up, strapped down).

  • Don’t let the cylinders get too hot in the service vehicle.

  • Avoid fumes and inhaling vapors in an enclosed space; like any other refrigerant, 410A displaces oxygen.

    Craig Walker, a Carrier service training instructor based in San Francisco, CA, pointed out that the new equipment is well labeled to show that 410A is what’s in the system.

    “Everything is done in rose color, which was designated for R-410A,” he said, pointing out that R-22’s color designation is green.

    “If the wrong gauge set is used, the higher pressure could cause the 410A to spray out, possibly hitting the contractor or tech and causing freeze-burn,” he said. “There have been no accidents that I’m aware of. Distributors are doing an excellent job of training contractors and service/installation technicians.

    “Safety is stressed over and over,” Walker said. “When they leave the lab, we can’t make them do it. But we hope they will remember.”

    Most of Carrier’s product training has been taking place at the distributor level, stated Walker. “Most have mandated that their service people attend in order to sell and service 410A systems.”


    There are plenty of similarities between the two refrigerants. Rasmussen explained that because of similarities both in operating characteristics and equipment, “Our training is twofold, covering both 410A and 22.” It includes thermodynamics and refrigerant training.

    “We spend some time showing temperature and pressure charts, say at 40 degrees F, showing the differences in saturated pressure between the two refrigerants. Initially we show that 410A operating pressures run 60% to 70% higher than R-22,” he said.

    Among other benefits, contractors see that working with 410A unitary systems “is not a lot different than what they’re doing with 22,” Rasmussen said. “There are the same superheat/subcooling levels as 22. Glide on 410A is minimal.

    “R-410A has to be charged in liquid state,” he said, but “the two refrigerants that comprise it boil at close to the same temperature. So for slight leaks, R-410A can be topped off.”

    Word of caution: Just make sure it’s done while the 410A is in a liquid state.

    Walker agreed that small 410A system leaks can be topped off. “When in doubt, we tell them to recover all the refrigerant and recharge it all in liquid state. But for small amounts, they probably could charge it in liquid state, then go back and check performance.”

    Puron® (the trade name of Carrier’s R-410A product) “has less than 0.3 degree of glide,” Walker said. “It’s a near azeotrope and can be treated as a single compound. This is a plus for service techs.”


    Besides the differences in operating pressures and resulting safety concerns, manufacturer training is focusing heavily on keeping the systems clean and dry. This is also important with R-22 systems, they point out, but it is critical for the polyolester oils (POEs) used with 410A.

    “There is nothing new here,” said Rasmussen, “but as techs, we’ve gotten a little lax. POE oils have a much greater affinity for water, so they can’t leave systems open.”

    Ask yourself: “Do you use a sling psychrometer to get indoor wetbulb readings? You need those for proper charging,” said Rasmussen. “Do you run a load calculation? You need to use a proper refrigerant line size and proper brazing techniques so that condensation cannot get into the oil.

    “R-22’s mineral oil has been much more forgiving,” he continued. “If you use sloppy techniques on 410A systems, you’ll get condensation in the system, get many callbacks, and may have to go through several driers.”

    In short, the callbacks can eat up the profits from the job.

    “It’s kind of fun,” Rasmussen said. “You’re standing there in front of the group, and as you go through the list of things not to do, they’re nodding their heads and you can see it in their eyes.”

    Walker said that Carrier’s Hvac Pro Mechanical Troubleshooting Course also teaches that POE oils are hygroscopic (absorb moisture). “That’s why it’s mandatory that they [servicers] replace the liquid-line drier.” Air in the system “would eventually cause acids and sludge due to the moisture content.” This eventually leads to compressor failure, he noted.

    “There is a need to bring back service procedures that kind of went lax,” said Walker. Technicians also need to be aware that “POE oils are not compatible with desiccants used in some driers. Liquid-line drier needs to be 100% molecular sieve,” he said. “That’s all they can use with Puron.”

    Rasmussen concluded, “Classes across the country have been very well attended. At first contractors may be grumbling. By the end of the class, they have a better understanding and a changed outlook.”

    What’s your experience with R-410A? Contact Barb Checket-Hanks at 313-368-5856; 313-368-5857 (fax); (e-mail).

    Publication date: 05/20/2002