As a lead-in to what's happening in the U.S. regarding hydrocarbon refrigerants:
As of 2011:
The EPA’s current rule on the use of hydrocarbon refrigerants (December 20, 2011; 76 FR 78832) can be read here:
Most of us have already read...(well, maybe not) or at least KNEW of that. It essentially states the ONLY acceptable use of hydrocarbon refrigerants are within the following applications and limits:
- R-600a and R-441A for NEW Household Refrigerators and Refrigerator/Freezers and limited to a system charge of 57 grams (2.0 ounces).
- R-290 for NEW Retail Food Refrigerators Freezers and limited to a system charge of 150 grams (5.3 ounces).
Here's the EPA's painfully long notice of proposed rulemaking entitled "Protection of Stratospheric Ozone: Listing of Substitutes for Refrigeration and Air Conditioning and Revision of the Venting Prohibition for Certain Refrigerant Substitutes":
The version posted on the U.S. government's federal register already reflects some proposed revisions (towards the end):
This “Notice of Proposed Rulemaking” (published on July 9, 2014) is listed in the Federal Register as a “Proposed Rule.” I didn’t do any exhaustive reading or research to determine the time it takes to become final. Since it's a PROPOSED rulemaking, it remains a dynamic document which will be subject to numerous revisions before it’s final. My uneducated guess is possibly in early 2015.
I took the liberty in attempting to summarize what that proposal says.
However, as an important preface for anyone considering any retrofitting/conversion to a flammable refrigerant:
"EPA is proposing that the flammable refrigerants considered in this proposal be limited to use only in new equipment that has been designed and manufactured specifically for use with the listed alternative refrigerant. We are proposing that these substitutes may be used only in new equipment that is designed to address concerns unique to flammable refrigerants. The flammable refrigerants were not submitted under the SNAP program to be used in retrofitted equipment, and no information was provided on how to address hazards of flammable refrigerants when used in equipment that was designed for non-flammable refrigerants. Introduction into interstate commerce of these refrigerants for use in existing equipment without giving timely and adequate notice to EPA would be in violation of section 612(e) of the CAA and the SNAP regulations at 40 CFR Part 82, Subpart G. In addition, if the rule is finalized as proposed, use of these refrigerants in existing equipment would be in violation of section 612(c) of the CAA and the corresponding SNAP regulations at 40 CFR Part 82, Subpart G."
So anyway, here's the high points in the EPA's proposal:
The proposal adds to these three refrigerants that are already accepted for use in NEW equipment:
- R-290 (propane)
- R-600A (isobutane)
- R-441A (hydrocarbon blend)
The refrigerants to be added to that list are:
- R-170 (ethane)
- HFC-32 (difluoromethane – a HFC with a methane base)
For refrigeration equipment, the items added will be:
- VENDING MACHINES (R-600A & R-441A with same charge limits as for commercial refrigeration).
- VERY LOW TEMP FREEZERS & THERMOSIPHONS (R-170 with same charge limits as for commercial refrigeration).
For residential & light commercial AC and heat pumps, where NONE were previously listed, the items added will be self-contained units such as:
- Window-mounted air conditioning units
- Packaged terminal AC (PTAC) units
- PORTABLE ROOM AC units (generally on wheels and may have an exhaust hose to a window)
So basically, comfort cooling/heat pump units (of limited sizes) designed for single-room use and don’t require any air distribution ducting or exterior refrigerant lines. Obviously, based upon their designs, equipment SPECIFICALLY EXCLUDED from this proposed ruling are central air conditioners, multi-split air conditioners and mini-split air conditioners.
The refrigerants for use in these AC/heat pump units will be R-441A and HFC-32. However, system charge limits will vary based upon their designed uses for a given sized space. The combination of a formula, the type of refrigerant and various tables would be employed by the manufacturer to determine the equipment charge limits. Additionally:
“Although using a formula to determine the maximum charge size and minimum room size is appropriate from an engineering perspective, it does not ensure that a consumer will select an appropriate AC unit for the size of their room. It is likely that some consumers may be unaware of the exact size of the room to be cooled and thus may select an inappropriately sized AC unit that increases the flammability risk. A consumer may believe that a larger, more powerful AC unit will provide better, faster cooling and therefore may select an inappropriately sized AC unit that increases the flammability risk. To address these concerns, EPA proposes to supplement the charge size guidelines in Appendix F of UL 484 with a use condition that restricts the maximum refrigerant charge of equipment based upon the cooling capacity needed, in British thermal units (BTU) per hour. Equipment manufacturers would be responsible for designing equipment below a maximum charge size consistent with the intended cooling capacity. This would allow the manufacturer, who has greater understanding of the issue than a consumer, to address the issue in a manner under the manufacturer's control. Placing the burden on the manufacturer also provides a better means for EPA to ensure compliance and thus to ensure that the risk to human health will not be greater than that posed by other available substitutes.”
Other high points in this proposed ruling:
Venting – All HC refrigerants are considered to be non-hazardous to our environment and can therefore be vented when conditions are safe to do so (i.e., safeguards to prevent ignition of the flammable refrigerant or conditions that can cause asphyxiation of personnel). A side note here that one of our forum members, who is HC-refrigerant trained, was issued a “vessel” to recover refrigerant INTO so that he could then take it outside and vent it into the air. HOWEVER, excluded from this exception is HFC-32, which is are currently subject to the venting prohibition.
Identification - Along with specified system markings, color-coding and labelling, the EPA recommends separate service fittings (my guess is they mean SPECIALLIZED fittings). That was merely a recommendation since they recognize that the size of the equipment affected is usually hermetically sealed at the factory.
Training -The EPA also recommends that technicians be specifically trained and certified for handling flammable refrigerants. They recognize that RSES has become the forerunner in that endeavor. Additionally:
"The EPA intends to update the CAA Section 608 technician certification test bank provided to approved organizations that administer the certification exams in accordance with 40 CFR 82.161 to specifically include questions concerning flammable refrigerant substitutes."