ICC announced the publication of the 2021 International Plumbing Code (IPC) and International Mechanical Code (IMC). A little known secret that occurs in the code business is before a code gets published, it is reviewed by the Code Correlating Committee (CCC). The purpose of the CCC is to correct mistakes that occur when a code change modifies one section yet fails to modify a companion section. Or, if two code changes result in a conflict in the code. If the code is not correlated, it may not make sense; or it may be confusing regarding the application of the requirements.

Basically, the CCC is supposed to make sure that the code does not look ridiculous with known mistakes. That would be a problem for the model code group. In many ways, the CCC is an immensely powerful committee, having the ability to modify code text for consistency and correctness. 

Unfortunately for ICC, the CCC failed to correlate the 2021 International Mechanical Code. As a result, the code has a major error. ICC will be asking states to adopt the code with this error. The question becomes, “Should the states adopt a code with a known error, or should the states simply wait until the 2024 code in the hopes that ICC properly correlates the code requirements?”

One of the hottest issues has been the introduction of low global warming potential (low GWP) refrigerants. Currently, every refrigerant found to be a reasonable and reliable low GWP refrigerant for direct systems falls into the category of Group A2L, which is identified by ASHRAE as lower flammability refrigerants. 

ASHRAE uses an alphanumerical means of classifying refrigerants. A indicates a lower toxicity refrigerant; B indicates a higher toxicity refrigerant. The number indicates the flammability of the refrigerant. Number 1 means no flame propagation. While Group A1 refrigerants may burn, such as R-22 and R-410A, they do not sustain a propagating flame. As the numbers go up, so does the flammability. As a lower flammability refrigerant, A2L refrigerants burn, but rather poorly. 

While the refrigerant industry recognizes the need to move in the direction of low GWP refrigerants, not every producer and manufacturer has supported the change. Some manufacturers have shown up at code hearings opposing any changes to the Mechanical Code regarding the acceptance of Group A2L refrigerants. 

While these companies have opposed specific changes that use the term A2L, they have not paid much attention to other code changes related to refrigerants. This is why the code is in desperate need of correlation. 

The ICC membership correctly accepted a code change that modified how refrigerants are classified during the first code change cycle (Cycle A). In the definitions, 2L is listed as a separate class of refrigerant. The companies did not oppose this code change. However, one of Honeywell’s consultants stated, “Definitions are advisory, they are not code requirements.” What? Since when have definitions not been an important part of the code?

The other changes that impacted the code were the references to ASHRAE 15 and ASHRAE 34. The 2019 edition of both standards were added in the second code change cycle (Cycle B), resulting in them being referenced in the 2021 IMC. ASHRAE 34-2019 was modified to identify 2L refrigerants as a separate class of refrigerants. Hence, both the definition in the IMC and ASHRAE 34 are consistent. 

In further identifying A2L and B2L refrigerants as a separate class of refrigerants, Honeywell’s consultant submitted code changes — on their behalf — listing A2L and B2L for use in machinery rooms. When you read the 2021 IMC, there are machinery room requirements for Group A2L and B2L refrigerants. Similarly, there are new piping requirements that include special provisions for Group A2L and B2L refrigerants. 

The big problem develops when you read the section on refrigerant classification — Section 1103.1 — of the IMC. This section states that refrigerants are to be classified in accordance with ASHRAE 34. That’s fine until it sends the code users to Table 1103.1, somewhat indicating that the table is consistent with ASHRAE 34. When you look for a refrigerant classified as A2L or B2L, you cannot find one in the table. These refrigerants apparently do not exist. 

One of the more well-known A2L refrigerants is R-32, which is a low GWP refrigerant. The reason we are familiar with R-32 is because it is 50% of the blend in R-410A, the other 50% being R-125. When you search for R-32 in Table 1103.1, the refrigerant is listed as an A2 refrigerant with a superscript note. When you read the note, it says that ASHRAE 34 classifies the refrigerant as a 2L, which is a subclass of Class 2. It is not a subclass; both the definition and the reference to ASHRAE 34 identify 2L refrigerants, both A2L and B2L, as a standalone class of refrigerant.

I feel sorry for any inspector faced with questions regarding this issue. How do you classify R-32 and similar low GWP refrigerants? Are they A2L, like the rest of the world understands, or are they A2, a subclass, as incorrectly listed in a note to a table that supposedly is taken from ASHRAE 34?

When CCC was asked to correlate the requirements, they declared it was not a correlation issue. It is too controversial an issue based on recent membership votes. What? Isn’t the CCC supposed to tackle controversial issues so that the code matches real life? By not correlating the table, the International Mechanical Code does not have the same classification as the rest of the world for these refrigerants. Why bother with the CCC if they are not going to take up errors that are too hot to handle?

I was curious so I looked up the ICC policy for the Code Correlating Committee. One of the requirements reads: “Resolve technical or editorial inconsistencies between multiple actions taken during the code development process by making appropriate changes to the text of the affected codes. Procedures for resolving these inconsistencies shall be in accordance with Section 7.0.” Oops, I guess they failed to follow their own procedures.

The solution to this problem is for states and local jurisdictions to simply delete Table 1103.1 and any reference to the table. The references should be changed to ASHRAE 34, since that is the main reference in Section 1103.1. The IMC was very clear in stating that ASHRAE 34 is the standard that regulates the classification of refrigerants and the refrigerant concentration limit (RCL).

Fortunately for ICC, the 2021 IMC directly references ASHRAE 15 for refrigerant systems. This allows the engineer and code official to go directly to ASHRAE 15 when using low GWP refrigerants. Until the IMC is properly updated and corrected, at least the reference to ASHRAE 15 provides the necessary requirements for the use of low GWP refrigerants. 

As one observer noted, this is what happens when the ICC loads the CCC with building and fire officials who are not well versed on the plumbing or mechanical code. In the future, perhaps the ICC Code Correlating Committee will pay closer attention to the Mechanical Code issues. 

Note: The views expressed here are strictly those of the author and do not necessarily represent PM Engineer or BNP Media.