The HFC phasedown started this year with a 10% production cut, which is starting to affect the price of refrigerants such as R-410A. When the additional 30% cut comes in 2024, expect prices to rise even more, and availability of virgin refrigerant may become more of an issue. The production cuts are part of the federal AIM Act and are meant to encourage a safe and speedy transition to lower-GWP refrigerants, several of which are mildly flammable (A2L).

The problem is that most building codes do not allow the installation of comfort cooling equipment containing A2L refrigerants. The 2024 international building code update will likely include the use of these mildly flammable refrigerants, but some states are not waiting. Instead, many are updating their state codes to allow the use of A2L refrigerants in air conditioners and heat pumps, with Florida, Oregon, North Carolina, and Washington leading the way. In those four states, it is already possible to buy and install equipment containing this alternative refrigerant.

Given the growing availability of A2L equipment, the HVAC Excellence National HVACR Education Conference included a hands-on demonstration showing how to install a mini-split heat pump containing R-32. Other sessions at the conference also discussed the safe use of mildly flammable refrigerants that will soon be replacing R-410A in new comfort cooling equipment.

Demo Highlights

Over the course of the full-day R-32 mini-split installation demonstration, there was a discussion of the tools needed to install an A2L system. According to Mark Harte, technical training manager at Daikin North America, many of the tools will be the same as those used for R-410A systems, such as a heat pump gauge, flaring tool, flare gauge, deburring tool, tubing cutter, torque wrench, HEX set, and core remover tool. Additional tools required include a nitrogen regulator (capable of pressurizing the system to 550 psig), an A2L-compatible evacuation pump, micron gauge, and digital scale.

“There’s a lot of talk going on that technicians are going to need all brand new tools in order to install an R-32 system, but I want to debunk that right now,” said Harte. “Installing an R-32 unit is essentially the same as installing an R-410A system.”

Harte also pointed out that for R-32, only recovery cylinders with pressure resistance to 696 psig can be used, and being a flammable refrigerant, the bottle will likely have a left-handed thread. In that case, an adapter will be needed to convert left thread to right thread, for use with manifolds. In addition, a combustible gas monitor should be carried and turned on when entering an R-32 service area, and no service should begin until the area has been checked for flammable refrigerants. Monitors that use audible signals are recommended, and the monitor should remain on for the duration of work. A Class B dry powder-type fire extinguisher should also be kept nearby when working with A2L refrigerants.

Once the indoor and outdoor units are installed, nitrogen pressure testing is mandatory in order to find any refrigerant leaks, said Matt Stapp, technical trainer at Daikin North America. If a contractor does not properly pressure test the system and it has a leak, a callback is all but guaranteed, which costs time and money. For the R-32 system, the recommendation is to pressure test in three stages, after verifying that all the stop valves are securely closed.

“For the first stage, we recommend that you go to 150 psi and let it set for about three minutes,” said Stapp. “This will catch a forgotten or bad flare -- basically the more sizeable leaks. After that, go to 325 psi and hold it for five minutes. This will catch the smaller leaks. The third stage is to take it to 550 psi and do a two-hour hold. I know this can be a lot to ask of a contractor doing residential installs, but there are other things you can do on a job site during that time. These stages are the sweet spots to find the large, medium, and small leaks, and it’s very important.”

Stapp stressed that if there is a leak in the line set, do not add refrigerant to the system. He also recommended using a commercial-grade leak detector solution to do a soap bubble test while the system is at 100 psi. If the pressure is higher than that, he said, it will blow the solution off before a leak can be found.

Differences

Pressure testing with nitrogen to identify leaks is one of the three main differences between the installation of an R-410A and an A2L system (the other two are purging with an inert gas and evacuating the system). However, as Jason Obrzut, director of industry standards and relations at ESCO Group, noted in a different session at the conference, these differences will be nothing new for contractors already following best practices.

“With A1s, an evacuation was not required by code. Purging with an inert gas was again, not required. Leak testing the unit was not a code requirement. However, these were best practices,” he said. “If you were doing these things already, you're not going to see a difference when you're installing or servicing an A2L system. Remember, these are now requirements -- not by the manufacturer, by code.”

He added that when installing A2L equipment, most of the differences are going to take place before the equipment is even installed. That’s because it is necessary to evaluate the installation site to make sure the unit can be used in a certain location. Essentially there are going to be use restrictions and limitations based on the size of the charge, which will be spelled out by the manufacturer in the accompanying manuals.

That’s another difference with A2L units -- they will come with three manuals: a user’s manual, an installation manual, and a disposal manual. These are required by UL Standard 60335-2-40, and unlike manuals that accompanied R-410A or R-22 equipment, the information will be certified, tested, and verified by the testing laboratory to verify it is accurate. The three manuals must always stay with the equipment.

“The installation manual, for example, will include specific information such as charging charts, so technicians don’t have to do the trigonometry and algebraic computations to figure out the internal cubic volume of the space,” said Obrzut. “The chart will spell out the square footage, the Btu of the unit, and what the maximum charge can be. If the charge exceeds that limit, then technicians will need to alter the installation in a way that shortens the line set. There will also be use restrictions, such as it can’t be installed under a deck.”

The service manual will detail how much refrigerant can be added based on the leak history, as well as pressure test and vacuum requirements. As Obrzut noted, all of this information has been predetermined and passed through a certification process by the time it hits a service truck.

“A lot of technicians use the manual as something to kneel on, but they need to read it,” he said. “Open that book and see what kind of information is there – the charging charts, use applications, etc. It’s all there, so techs don’t have to sit there and calculate the maximum charge or figure out whether or not a unit can be used in a particular building.”

It is also important to label match the indoor and outdoor unit. While some contractors may install mismatched units with R-410A or R-22, that is not allowed with A2L equipment, said Obrzut. “The label on the indoor unit must match the label on the outdoor unit, with the same refrigerant, the same rating, all of that. You can’t make Frankenunits.”

To thoroughly understand how to install and service R-32 units, technicians should take a general class on A2Ls, such as those offered by ESCO Group or ACCA, as well as manufacturer-specific training. And the sooner the better, said Obrzut.

“The phasedown has already started with the 10% production cut of HFCs in January,” he said. “If you think you have a few years to get ready for the transition, you don’t. It’s already started.”