IEC hydrocarbon charges ACs
Charge limits for home ACs and heat pumps have increased dramatically with added safety measures, explained Asbjørn Vonsild at the ATMO World Summit

Higher Hydrocarbon Charges Unanimously Approved in IEC Standard for Home ACs and Heat Pumps

As much as 988g of R290 can be used in split AC systems with certain enhancements, according to new IEC 60335-2-40 standard.

Higher charge limits for propane (R290) and other flammable refrigerants in household air conditioners, heat pumps and dehumidifiers have been approved in a unanimous vote by countries in the subcommittee overseeing the International Electrotechnical Commission (IEC) safety standard for these appliances.

In a post in the IEC website, subcommittee (SC) 61D announced approval of the changes for the global safety standard, IEC 60335-2-40 ED7, based on a unanimous 24 positive votes for the FDIS (final draft international standard) by P (participating)-Member countries as well as zero negative votes by both P-Members and O (Observing)-Member countries. A minimum 66.7% positive vote by P-Members, as well as a maximum 25% negative vote by all members, is required for approval. The voting period for the FDIS was March 18 to April 29.

A working group (WG21) has been managing the voting process.

Publication of the updated standard on the IEC website is planned for June 24, though it could be one to two weeks earlier or later, said Asbjørn Vonsild, head of Vejle, Denmark-based Vonsild Consulting, and convener of WG21.

The long-awaited approval of the higher charge limits for a wide range of flammable refrigerants – A3 (flammable), A2 (low flammable) and A2L (lower flammable) – in household ACs and heat pumps is the culmination of a seven-year process. It is expected to help accelerate the transition from high-GWP HFC refrigerants to flammable refrigerants, notably R290.

“This is a very important milestone for the industry, since this standard will enable the phase out of R410A in most applications,” said Vonsild. “It enables a broader use of flammable refrigerants.”

“As far as hydrocarbons are concerned, it represents one of the most significant changes in RACHP safety standards for 20 years,” said Daniel Colbourne, co-manager of U.K. refrigerant consultancy Re-Phridge LTD.

The IEC 60335-2-40 ED7 standard follows the approval of higher charge limits of hydrocarbons in self-contained commercial cabinets (IEC 60335-2-89) in 2019.

Unanimity a good sign for country adoption

While the FDIS vote was unanimous, an earlier vote in 2020 for the CDV (committee draft for vote) version included two negative votes by P-Members (Japan and Malaysia) and one abstention (Denmark).

As with all IEC standards, the IEC 60335-2-40 ED7 standard still needs to be adopted by individual countries. That the FDIS vote was unanimous “signals that this is important for the industry in many countries, and I expect that the industry will push for local adoption,” said Vonsild, “This will surely help getting the standard adopted at country level.”

At the ATMO World Summit on March 30 (organized by ATMOsphere, publisher of, Vonsild explained the process by which the IEC 60335-2-40 ED7 standard would be adopted in the EU. The primary method is for the European Commission (EC) to publish the EN 60335-2-40 ED7 as a “harmonized standard,” which he said would take two to three years. In the meantime, equipment manufacturers could apply the higher charge limits of the new standard by using a “risk assessment – a simple argument that a new edition of a harmonized standard will be at least as safe as an old (ED6) standard,” said Volsild.

Europe has another EN standard, EN 378, that allows up to 1.5kg (3.3lbs) of R290 indoors, but is less suitable for factory-built systems – the majority of home ACs and heat pumps – and have stricter room size requirements. EN378 is also in the process of getting updated.

In the U.S., the next step will be forming a CANENA Technical Harmonization Committee (THC) to discuss proposals for adopting the changes into the next edition of the North American safety standards, including UL 60335-2-40, explained Christina Starr, Senior Policy Analyst, Climate Campaign, for the Washington, D.C.-based Environmental Investigation Agency (EIA).

“If U.S. industry stakeholders embrace this new Edition 7 and initiate the process for harmonization, we could see residential and light commercial heat pumps and ACs using R290 or other hydrocarbon refrigerants on the market in the next five years,” said Starr.

“It gives me great hope that U.S. consumers can potentially have HFC-free options for their residential AC or heat pump in time to make a difference during this critical decade for climate action,” she added.

988g max charge inside

Under the previous iteration of IEC 60335-2-40 (ED6), a 20m2 (215ft2) room with a 2.2m (7.2ft) ceiling height could use a wall-mounted AC split system with 334g (0.7lbs) of R290. That is true of the new proposal, except that now additional safety measures allow larger charges to be used. “For an efficient split AC system, you need 450 to 500 grams [0.99 to 1.1lbs],” said Vonsild.

For example, with “enhanced tightness,” the system could use 585g (1.3lbs) of R290, and with enhanced circulation airflow (via fans), 836g (1.8lbs) could be employed, according to a chart Vonsild presented at the ATMO World Summit. The maximum amount of R290 that could be used, in rooms starting at about 23m2 (247.6ft2) is 988g (2.2lbs).

Enhanced tightness “is related to using best practices in the manufacturing of the units,” allowing higher charges and lower airflow requirements, explained Vonsild. “Enhanced tightness in the -2-40 [standard] also implies that the compressor is placed outside the occupied space.”

Another way of keeping the refrigerant charge mostly in the outdoor section of a split system – and thus limiting the “releasable charge” inside – is to use safety shut-off valves, said Vonsild, adding, “Only the flammable refrigerant charge that will leak to the occupied space is considered to cause a significant hazard.”

With proper air flow, a leaked refrigerant won’t be able to fall to the floor and accumulate to ignition levels but will be distributed throughout the room, allowing more refrigerant to be used. “It does not take a lot of airflow to do it,” said Vonsild. This was developed “specifically for A3 refrigerants,” he added.

The additional measures needed for higher charges are not “a significant barrier,” noted Vonsild. “Split ACs have fans built into them, so providing airflow is not a big issue.”

The IEC 60335-2-40 ED7 standard also applies to self-contained window units. But for these units some of the charge limit options require “careful design” to prevent leaks in the outdoor parts from entering the room, said Vonsild.

“If U.S. industry stakeholders embrace this new Edition 7 and initiate the process for harmonization, we could see residential and light commercial heat pumps and ACs using R290 or other hydrocarbon refrigerants on the market in the next five years.”

Christina Starr, EIA

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