ASHRAE Journal - January 2021 - 42

TECHNICAL FEATURE

enforcement in the residential sector is generally weak.‡
There is also a lack of consistency concerning refrigerant leakage standards and testing protocols. The
Northeast Energy Efﬁciency Partnerships (NEEP) publishes a generally excellent " Guide to Installing AirSource Heat Pumps in Cold Climates, " referenced as a
best-practice document by several state and utility programs.7 The NEEP guide speciﬁes a standing pressure test
but does not give details on duration or bubble testing. It
also speciﬁes an evacuation target below 500 microns, but
does not require a vacuum decay test.
The Building Performance Institute's (BPI) " Technical
Standards for the Air Conditioning & Heat Pump
Professional, " also used by some state programs, does not
discuss the standing pressure test.8 BPI sets the default
evacuation target at 500 microns and the acceptable rise
at 300 microns within ﬁve minutes.
The Air Conditioning Contractors of America (ACCA)
Standard 5, HVAC Quality Installation Speciﬁcation, requires
" leak-free circuit: achieved by purging with nitrogen during brazing, conducting a nitrogen pressure test, evacuating (triple) and holding to 500 microns or less. " 9 The
ACCA standard, which is also an ANSI standard, does
not provide a detailed protocol for the pressure test or
vacuum decay test. Groups like NEEP, ACCA, ANSI, and
BPI can help reduce refrigerant leaks by clarifying, aligning and strengthening their standards.
State and utility programs providing incentives and
rebates for heat pumps can also adopt policies to reduce
refrigerant leakage:
* Make leak prevention a priority in program manuals and contractor trainings;
* Require time/location-stamped photographs of best
practices (torque wrenches, bubble testing, and electronic leak detection) on each jobsite;
* Require time/location-stamped reports of vacuum
decay tests generated by mobile apps;
* Develop a quality assurance program that tracks
leak occurrence by contractor and provides corrective
training as needed; and
* Work with supply houses and/or refrigerant management companies to provide incentives and operational
support for recycling or disposal of used refrigerants.
Contracting companies can also take leadership in
‡The

act also contains regulations on allowable leak rates, but these
apply only to larger systems containing more than 50 lb (23 kg) of
ozone-depleting refrigerants.

ASHRAE JOURNAL

ashrae.org

JAN UARY 2021

reducing refrigerant leaks. In doing so, they will beneﬁt the environment, their customers, and their own
bottom line. Efforts begin with training staff in both
the " why " and the best practices of leak prevention.
Managers should work with technicians to build testing
into their workﬂow-for example, assigning a helper to
perform bubble testing and begin evacuation while the
lead installer completes electrical wiring.
Technicians should be equipped with good-quality
tools, including wireless micron gauges and electronic
leak detectors. Checklists, digital photographs and appgenerated reports can be used to document that jobs are
done right. Although a good leak-prevention program
requires investment in equipment and training, and
sometimes a little extra time on-site, it will pay for itself
in better performance and fewer callbacks.

Conclusion

Refrigerant leaks have a major impact on the environment, speciﬁcally on global warming. Best practices in
installation and service can measurably reduce leaks.
Such best practices require harmonization between
standards-setting organizations, manufacturers'
requirements, engineering speciﬁcations and contractor training. Harmonized best practices will reduce leaks
and could even expedite installation by eliminating conﬂicting requirements between standards, manufacturer
requirements and typical design speciﬁcations.

References

1. Johnson, S.K. 2020. " Few Exceptions to the Rule that Going Electric
Reduces Emissions. " ArsTechnical.com. https://tinyurl.com/y6o4fdec
2. IPCC. 2007. " Climate Change 2007: The Physical Science Basis.
Contribution of Working Group I to the Fourth Assessment Report
of the Intergovernmental Panel on Climate Change. " S. Solomon, D.
Qin, M. Manning, Z. Chen, et al., eds. Cambridge, UK, and New York:
Cambridge University Press.
3. Baddeley, A. 2014. " Impacts of Leakage from Refrigerants in
Heat Pumps. " Eunomia.com. https://tinyurl.com/yy8dkkqw
4. Hawken, P. 2017. Drawdown: The Most Comprehensive Plan Ever
Proposed to Reverse Global Warming. Penguin Books.
5. Psioda, Z. " HVAC Shop Talk: Leaking HVAC
Coil Passes Vacuum Test. " YouTube.com. https://
tinyurl.com/y2cc4klh
6. Harrod, J. 2020. " Performance testing
ductless systems. " Building Performance Journal
https://bit.ly/3khhdC5
(Fall):42-46.
Rate this Article
7. NEEP. 2020. " Guide to Installing AirSource Heat Pumps in Cold Climates. " Northeast Energy Efﬁciency
Partnerships. https://tinyurl.com/y4wn2lm8
8. BPI. 2003. " Technical Standards for the Air Conditioning
and Heat Pump Professional. " Building Performance Institute.
https://tinyurl.com/y2vexv46
9. ACCA. 2015. " ACCA Standard 5, HVAC Quality Installation Speciﬁcation. " Air Conditioning Contractors of America.
https://tinyurl.com/y5uwvezm

http://www.ArsTechnical.com https://www.tinyurl.com/y6o4fdec http://www.Eunomia.com https://www.tinyurl.com/yy8dkkqw http://www.YouTube.com https://www.tinyurl.com/y2cc4klh https://www.tinyurl.com/y2cc4klh https://www.bit.ly/3khhdC5 https://www.tinyurl.com/y4wn2lm8 https://www.tinyurl.com/y2vexv46 https://www.tinyurl.com/y5uwvezm https://www.ashrae.org/

ASHRAE Journal - January 2021

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