EIA supports ASHRAE proposal for 4.9kg propane charge in outdoor heat pumps in U.S.

September 26, 2023

The Washington, D.C., branch of the Environmental Investigation Agency (EIA) has thrown its support behind a proposal issued by ASHRAE to amend its 15.2-2022Safety Standard for Refrigeration Systems inResidential Applications to allow up to 4.9kg (10.9lbs) of flammable (A3) refrigerants like propane (R290) in outdoor heat pumps and air conditioners in the U.S.

The Proposed Addendum E to Standard 15.2-2022, in an advisory public review draft, completed a 45-day public review period on September 18. If approved by ASHRAE, the charge limit would also need to be endorsed by UL under its 60335-2-40 standard, and then by the U.S. Environmental Protection Agency (EPA).

The EIA’s comments were submitted by Christina Starr, Senior Manager, EIA-US.

“EIA strongly supports the advancement and approval of this Advisory Public Review draft by the SSPC 15 Committee to update the ASHRAE 15.2 provisions for enabling A3 [flammable] refrigerants in low-probability systems outdoors,” wrote Starr. A low-probability refrigeration system is one in which the basic design or the location of components is such that a leakage of refrigerantfrom a failed connection, seal or component will be released outdoors.

“This proposal provides for the safe installation and use of ultra-low global warming potential refrigerants such as propane and other hydrocarbons in indirect outdoor systems,” she continued.

Starr noted that the proposed 4.9kg charge limit applies to outdoor indirect systems, such as air-to-water (monobloc) heat pumps. In these systems, “the refrigerant remains outdoors and is installed to avoid any possible nearby ventilation or other openings to the occupied space in order to ensure a flammable refrigerant does not enter the occupied space in the event of a leak.”

EIA supports the harmonization of U.S. safety standards and building codes with other international equivalents that already enable safe use of A3 refrigerants in similar outdoor equipment. Current international standards and codes in place globally, including IEC 60335-2-40, allow up to a 4.9kg charge size of A3 refrigerant outdoors. “Updates to ASHRAE 15.2 and UL 60335-2-40 must be prioritized to bring the U.S. market into step with the cost-effective and ecofriendly technologies being adopted throughout Europe and other regions globally,” Starr wrote.

Existing regulation in the U.S. only permits 114g (0.3lb) of propane in fixed or non-fixed heat pump and AC units (including outdoors). At the ATMO America conference in June, Starr urged HVAC&R stakeholders in the U.S. to get engaged in the process of setting national standards and codes for expanding the use of hydrocarbons in air-conditioning and heat pumps.

In Europe, companies like Panasonic have released monobloc R290 heat pumps for residential use.

Safe retrofit to replace oil/gas boilers

Indirect air-to-water heat pumps using R290 “show great promise as safe, cost-effective, efficient, and climate-friendly solutions for residential heat pumps,” Starr noted. “This technology will support building decarbonization and introduction of heat pumps in existing buildings, particularly as convenient and cost-effective building retrofits for replacing boilers that rely on hydronic delivery systems for heating.”

Monobloc heat pump systems use R290 as the primary refrigerant in a closed loop system located outdoors or on rooftops and a secondary nonflammable fluid such as water to deliver heating and hot water for residential use inside the building. Hydronic systems require no expensive duct work installation, while also avoiding the need to install or replace refrigerant line sets required for ductless split systems, she added.

“The thermodynamic properties of R290 make it the most efficient low-GWP refrigerant option that can provide adequate capacity and efficiency in this type of building retrofit application,” she wrote.

The Addendum E proposal ensures that any R290 leak would not enter the occupied space and form a flammable concentration. “Any such leak would remain outdoors and disperse rapidly in open air and equipment installed per code such that nearby ignition sources or points of venting into the building are avoided,” observed Starr.

Moreover, these R290 heat pumps would enable replacement of flammable heating systems using fossil fuels such as oil or gas boilers, which typically contain large quantities of flammable material located inside an occupied building, “with risk of fire or explosion incidents if not properly managed,” she noted.

Starr also contrasted the use of A3 refrigerants with that of A2L (less flammable refrigerants), which are typically blends of HFCs and HFOs. A2L refrigerants would typically be used in a direct split system design using a much larger quantity of refrigerant to be delivered as the direct heat transfer fluid piped inside the occupied space. “Considering that HFC-HFOs when ignited produce a toxic hydrofluoric acid (HF) byproduct, the risks to building occupants and fire fighters would be considerably greater than a standard that encourages the alternative use of heat pumps systems using flammable refrigerant outdoors,” Starr wrote.