UK: Daikin is planning to introduce the “mildly flammable” low GWP R32 in its commercial Sky Air air conditioning units as the next step in a roll-out of low GWP refrigerants. 

Although no date is given for the introduction of R32 Sky Air units, this, along with other information on the Japanese manufacturer’s views on low GWP refrigerants, is revealed in a new explanatory white paper published by Daikin UK in preparation for the launch of R32 units in the UK next year.

Daikin’s Ururu Sarara residential split system is readily available in the Far East, India and mainland Europe, with over 2,000,000 units sold since 2012. In the UK, however, Daikin has held back its introduction to ensure that installers are fully conversant with dealing with this new refrigerant. Training courses on the new “mildly flammable gas” are expected to begin this autumn.

Daikin will introduce the first R32 split systems with capacities less than 7kW early next year in the UK but a general introduction of lower GWP replacements for R410A is planned across the product range globally.

The white paper reveals that Daikin is currently also planning to introduce R32 to its Sky Air light commercial range (with capacities between 7kW and 14kW). Development is also underway to use “next generation” refrigerants in Daikin VRV systems, although the timescale and the identity of the likely refrigerants has not been decided.

Mounting pressure

Pressure is mounting worldwide on the use of high GWP refrigerants. In Europe, the F-gas revision to be introduced on January 1 will see a ban on certain high GWP refrigerants in some applications and a unilateral phase-down on HFC consumption. It seems likely that the rest of the world will follow with support growing for a worldwide phase-down of HFCs under the Montreal Protocol. Although not in the immediate legislation firing-line, R410A and its GWP of 2088 would be considered by many to be a medium to high GWP gas.

However, under the new F-gas regulations in Europe refrigerants with a GWP over 750 will be banned in small splits (under 3kg charge) by 2025, meaning that R410A will no longer be acceptable.

The European F-gas regulations also include a phase-down timetable which will see HFC consumption reduced to just 21% of current consumption levels by 2030. As these figures are based on CO2 equivalents, the industry will need to find energy efficient alternatives to some of the current most popular higher GWP gases, like R410A, where applications allow.

Daikin stresses in its white paper that R410A will still be available for some time to come ensuring continuity of supply and after-sales support for existing customers: “As split systems have a typical working life of 10 years, customers deciding to stick with R410A should be confident that their system will be unaffected by the HFC phase-down (with regard to maintenance, spares and re-charging of systems). It must be remembered that even after 2030, it will still be possible to use R410A, although it is likely that supplies could become limited.”

As revealed by the Cooling Post earlier this month, manufacturers and research institutes across Japan have been carrying out risk assessments on the use of R32 and R1234yf in VRF systems.

The introduction of these “mildly flammable” refrigerants in larger commercial systems is still hampered by international and national standards which limit the allowable charge size of flammable refrigerants in a single system. Daikin admits that it is currently developing VRV systems using “next generation” refrigerants but, as with its split systems, the company points out as R410A is not specifically banned customers can be confident that a VRV system installed in the next 5-10 years will still be compliant and serviceable for the 15-plus years of its working life.

Other Japanese manufacturers have also developed equipment running on R32 but it seem that Daikin will take the lead role with its introduction in Europe. The same was the case with VRF technology. Although by no means the only Japanese manufacturer with VRF systems in the late 80s, Daikin stole a march on its competitors by being the first to step into Europe with a technology which ultimately proved to be revolutionary.

The case Daikin puts forward for R32 seems a convincing one. R32 has a lower GWP than R410A (675 compared with R410A’s 2,088) and offers slightly better energy efficiency (6% higher in a 4kW system). It also uses similar technology and requires smaller charges than R410A, meaning heat exchangers and other components can be smaller, making equipment more compact (18% smaller when compared with a 4kW system using R410A). As a single component refrigerant, there are no problems with glide and it can also be easily reused and recycled.

Flammable

HFOs have been researched as potential R410A replacements but, although possessing the same toxicity/flammability rating (A2L) as R32, Daikin deems that their pressure and energy efficiency makes them unsuitable for replacing R410A in air conditioners and heat pumps.

It is that “mild flammability”, however, which raises the most concerns about R32 and something which Daikin UK seeks to allay in its white paper.

Daikin points out that R32 has a burning velocity of 6.7cm/s compared to propane’s burning velocity of 46cm/s. It refers to its own tests and those carried out by Suwa Tokyo University of Science which are said to show that even if combustion of R32 occurs (at concentrations of more than 320g/m3), it is not explosive and the possibility of fire spreading is extremely low.

If the current charge limits for R32 under European guidance in EN378 are followed and a complete charge were to leak into a confined space, Daikin says it is very unlikely to ignite from a spark created by operating a switch or capacitor.

During soldering/brazing work, Daikin maintains that the small flame that occurs from remaining gas in the system is actually caused by the oil and a similar behaviour to that currently experienced with R410A systems.

As with the HFOs, concerns have also been raised over the potential for the creation of hydrogen fluoride (HF) as a by-product of the ignition of R32. If exposed to high temperatures, R32 will decompose into carbon monoxide, carbon dioxide and hydrogen fluoride. The latter, when mixed with water, creates hydrofluoric acid, which is highly toxic.

But, as Daikin points out all HFC refrigerants will undergo the same process on exposure to high temperatures, including those used today.

“So while the risks cannot be ignored, they highlight the importance of safe working practices, regardless of the refrigerant being used,” it says.

“Regardless of the refrigerant gas being used, it is imperative that equipment is installed and charged by competent and well trained people,” Daikin insists. “This means installers should be F-gas certified and trained on the systems they are installing and the refrigerant gases being used.”

According to Daikin, the changes to installation procedures are relatively minor: “In essence, installation is the same, the pipework is the same (using flared connections) and pressure testing and leak testing are the same.”

Specific tools, such as gauges, manifolds, leak detectors and recovery systems, will be needed – which Daikin insists are now available.

“The key issue is that installers will now be handling a flammable gas, which means a new set of charging and recovery procedures need to be followed but nothing that will present a major challenge,” says Daikin.

For example, it insists that an R32 system must be ventilated during charging and recovery, to prevent a build-up of refrigerant, which could then be ignited by a naked flame. While this is not normally an issue, if an outdoor unit is being installed inside a building, then a suitably rated fan should be used to ventilate the area – but Daikin also notes that this is already a requirement for installing systems with R410A.

The introduction of R32 will present some challenges for industry but Daikin UK says it is working hard to help ensure installers are ready, providing clear information on the new refrigerant and offering training in its safe handling. Daikin UK is also providing advice to consultants and end-users to help them make informed choices when designing and selecting hvacr systems over the next 10 to 15 years.

“Education will be key,” says Daikin, and has begun developing installer training programmes that will cover the properties of the refrigerant and oils, cylinders, service and installation tools, as well as handling procedures, equipment installation and service.

“Installers need to ensure they are F-gas accredited, are fully aware of the new regulations coming in 2015 and are trained in handling R32 and installing any new systems. They should also keep up-to-date with the latest guidance from industry bodies such as REFCOM, ACRIB, IOR, F-Gas and DEFRA”

Copies of the document Introducing R32 are available for download here.

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Further reading:

R32 in VRF systems could be next – July 6, 2014
JAPAN: Air conditioning manufacturers in Japan could issue safety guidelines for the use of “mildly flammable” R32 in VRF systems as early as this autumn. Read more…

R32 not available until 2015 – February 11, 2014
UK: Daikin’s split system air conditioners running on R32 refrigerant will not be available in the UK until next year. Read more…