The Air-Conditioning, Heating and Refrigeration Institute (AHRI), based in Arlington, Virginia, has been selected to receive $2.5 million from the U.S. Department of Energy (DOE) as part of a collaborative effort to address “performance and safety concerns” for implementing air-to-water heat pumps in the U.S. market that use flammable (A3) refrigerants such as propane (R290).
The research will support the efforts of ASHRAE to evaluate a proposal to raise the charge limit of R290 in its safety standards for residential outdoor (indirect) heat pumps and air conditioners in the U.S. to 4.9kg, comparable to what is allowed in Europe.
The AHRI will work with Oak Ridge National Laboratory and the University of Maryland College Park on this project, which will “support the advancement of ultra-low global warming potential refrigerants by identifying technical requirements to resolve code and other potential deployment barriers for next-generation heat pumps,” said the DOE in an announcement on September 17 naming the 25 projects across 17 states selected for a total of $38.8 million in funding. Several of these involve the use of natural refrigerants such as R290 and CO2 (R744).
The projects were chosen to “research and develop high impact building technologies and practices” aimed at decarbonizing, reducing peak demand on the electric grid, enhancing resilience and lowering energy costs. Funding comes from the DOE’s Buildings Energy Efficiency Frontiers & Innovation Technologies (BENEFIT) opportunity.
“Great to see this! A number of important projects to advance adoption of natural refrigerants in HVAC,” said Christina Starr, Senior Manager, Climate for the Washington, D.C., office of the Environmental Investigation Agency (EIA), in a comment on LinkedIn.
The AHRI project was selected under the category called Design and Performance Evaluation for Secondary Loop Heat Pumps with GWP less than 10. “Look forward to working with leading experts from AHRI member companies, Oak Ridge National Laboratory, and the University of Maryland College Park on this important project,” said Xudong Wang, Vice President of Research for AHRI, in a LinkedIn post.
AHRI’s research, led by Wang, will support ASHRAE’s SSPC (Standing Standard Project Committee) 15.2 standards committee, which is overseeing the proposal to approve the use of up to 4.9kg of flammable refrigerants like R290 in outdoor heat pumps and air conditioners in the U.S. The proposal, called “Addendum E,” would increase the charge limit for A3 and A2 (less flammable) refrigerants in these HVAC applications, amending ASHRAE’s 15.2-2022 Safety Standard for Refrigeration Systems in Residential Applications. Existing regulation in the U.S. only permits 114g of propane in fixed or non-fixed heat pump and AC units (including outdoors).
It will most likely not be until “2025 or later” before the SSPC 15.2 committee approves Addendum E, said Jim VerShaw, chair of the committee and Chief Engineer, Residential HVAC for Trane Technologies, in an interview in March.
“Look forward to working with leading experts from AHRI member companies, Oak Ridge National Laboratory, and the University of Maryland College Park on this important project.”
Xudong Wang, Vice President of Research for AHRI
Addendum E, in an advisory public review draft, completed a 45-day public review period on September 18, 2023. 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).
On January 21, SPCC 15.2 met in Chicago prior to the start of the AHR Expo 2024 and did a “public review” of Addendum E. It decided that studies and tests on indirect HVAC systems using these refrigerants were needed to support an increase in charge. The Committee formed a working group, which developed a “work statement” to do computational fluid dynamics and verification testing with Wang leading that effort.
At an online meeting of SPCC 15.2 on March 1, the work statement was approved, and Wang said he would seek funding for the research. The working group will also be studying the European market, where residential outdoor heat pumps using 4.9kg of R290 are already provided by a number of companies.
EIA support
Last year, the Washington, D.C., branch of the EIA said it strongly supported approval of the proposed Addendum E. “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,” wrote Starr.
The EIA is behind 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.
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.”
