WSHPs Vital Role in Decarbonization Part 4: Phaseout of R410 and Other Refrigerants
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By Jake Gribbon, Strategic Market Executive, JMP Equipment Company
So far in this series, we’ve discussed the relevancy of Water Source Heat Pumps (WSHPs) in terms of their low Energy Use Intensity (EUI) and high coefficient of performance (COP). However, looming refrigeration regulatory changes are another reason WSHP systems could soon dominate the commercial HVAC landscape.
Currently, the most widely used refrigerant for HVAC is R410A, a hydrofluorocarbon gas. Although hydrofluorocarbons pose no direct threat to humans, they have a high global warming potential (GWP) due to their ability to trap heat. GWP is a metric used to describe how harmful a greenhouse gas is. To offer some perspective GWPs, methane has a GWP of 27-30, while R410A has a GWP of 2088.
GWP Limit Restriction on HFCs by Sector
Currently, the U.S. and countries worldwide are in the midst of an ambitiously timed phasedown of hydrofluorocarbons as part of the Montreal Protocol - Kigali Amendment 20, passed in the U.S. Senate in 2022. The most imminent changes facing our industry are shown here:
Most WSHP manufacturers are switching all pre-charged equipment to R-454B, a non-ozone-depleting hydrofluoroolefin gas. Manufacturers of other types of HVAC equipment must also comply, if not with R-454B, then some other hydrofluoroolefins (HFOs) or HFO blends that fall below the 700 GWP threshold. It is a matter of determining which non-ozone-depleting refrigerant marries best with their particular technology.
This transition is tricky because HFO-based refrigerants, also known as A2L refrigerants, are mildly flammable, whereas their hydrofluorocarbon predecessors are not. Depending on the system's refrigerant volume, a range of new safety measures set forth in ASHRAE 15 Safety Standard for Refrigeration Systems must be included.
Safety Measures and Exemptions
There are some possible exceptions to these safety measures. HVAC units with internal refrigeration circuits that contain less than 3.94 lbs of refrigerant may be exempt, depending on the concentration limit of the space being served. (Refer to Section 7 Restrictions on Refrigerant Use of ASHRAE 15 2022.) However, most WSHPs installed in typical commercial or multi-unit residential applications will contain less than 3.94 lbs. of refrigerant.
Any other equipment/system containing more than 3.94 lbs of refrigerant must be equipped with leak detection sensors to sense leaks anywhere they could occur. These systems must also possess the full range of leak mitigation capabilities prescribed in ASHRAE 15, 2022. These capabilities include but are not limited to alarms with relays that activate or deactivate equipment as needed if a leak is detected. Some adjustments will fall on manufacturers, while others involve the architect, engineer, contractor, facility personnel, and owner.
Figure 1 shows the measures that are required for WSHPs that contain more than 3.94 lbs. of refrigerant—roughly 4 tons and larger.
Distribution Refrigeration Systems Heavily Impacted
As mentioned, many WSPH systems may not require leak sensing or mitigation as long as the individual units contain at most 3.94 lbs of refrigerant and meet Section 7 of ASHRAE 15 2022. However, these new regulations will impact all distributed refrigeration piping systems, including popular VRF/VRV systems. This is because these systems distribute high volumes of refrigeration within the building envelope and occupied spaces. In a commercially sized application, distributed refrigerant systems may contain 8-9 lbs. of refrigerant per 12,000 BTU heating capacity. This number could be significantly higher depending on the space conditioning load.
Distributed refrigerant systems will be subject to safety requirements as dictated by ASHRAE 15 2022, ASHRAE 34, and U.L. 60335-2-40 requirements for flammable refrigerants in HVAC applications.* While a complete list of safety requirements is beyond the scope of this blog, these requirements will significantly influence the design and cost of the finished building. For example, in addition to a multitude of sensors, distributed refrigerant piping systems may require one or more of the following mitigation strategies for when a leak is detected:
Mechanical Ventilation. Operates continuously or initiated by the refrigerant detection system
Alarm Systems. Turn on upon refrigerant detection; 70dBA at 3m; visible and audible in the occupied space.
Safety Shut-off Valves. Normally closed; close within 30 seconds; seat leakage requirements; body leakage test.
In some cases, the fire safety measures will impact the architecture of the building. For instance, per ASHRAE 15, 2022, refrigerant piping that penetrates two or more floors/ceilings must be enclosed in a fire-rated shaft enclosure. Refer to section 9.12.1.5 Refrigeration Pipe Shafts, 9.12.2.2 Shaft Ventilation.
Only the Beginning
The phasing out of R-410 and other A1 refrigerants is just the beginning of a more all-inclusive phasedown of HFC refrigerants. Over the next 15 to 20 years, the U.S. and other adopters of the Kigali amendment will continue to enforce progressively stricter limits on HFC production and consumption, culminating in an 85% reduction in HFCs since 2011 -2013 (Figure 2).
According to the EPA, the projected emission reductions from this phasedown are “equivalent of 4.6 billion metric tons of carbon dioxide –equal to approximately three years of U.S. power sector emissions at 2019 levels. A global HFC phasedown is expected to avoid up to 0.5°C of global warming by 2100.” The wheels are in motion worldwide, with several European countries already ahead of the curve.
Education is the key to a smooth transition. As always, JMP is here to help. We are currently developing seminars to help get engineers up to speed on the new regulations and timelines. In the meantime, there are many online resources to help you get a handle on these changes. Here are just a few:
Protecting Our Climate by Reducing Use of HFCs
AHRI Refrigerant Webinar Series
The Refrigerant Transition Picks Up the Pace in 2023
U.L. 60335-2-40: Refrigerant Detection Sensor Requirements
*Currently, compliance of refrigerant detectors for flammable refrigerants in HVAC appliances is determined with the 4th edition of U.L. 60335-2-40 in section Annex L.L. For commercial refrigeration appliances, compliance is determined with the 2nd Edition of U.L. 60335-2-89 in section Annex 101.DVP.
