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A2L Refrigerant

B

brokenkeys

Member
Joined
Aug 24, 2015
Messages
81
Location
West Palm Beach, Florida
I did a quick search on here, but didn't see anything, so if this has already been discussed, please forgive me. If not... I just heard there is a federal requirement to change all refrigerants to A2L by 2025. A2L is flammable, which means there are detection requirements, venting requirements, lineset requirements, etc.

The 2024 ICC mechanical code includes numerous A2L refrigerant specific changes. The changes are outlined here: https://www.iccsafe.org/wp-content/..._Related_Changes_Redline_08.23.2022_FINAL.pdf

My questions are;

1. Has anyone here worked on a project that had to comply with these new A2L requirements?
1.a. If so, how did it go?
2. What happens in locations that don't adopt the latest mechanical code before the federal requirement kicks in?
2.a. FL, for instance, runs a few years behind the model codes. Does that mean there could be a period in the near future where buildings are being permitted & built with flammable A2L refrigerants without the detection and venting requirements outlined in the 2024 ICC code?
 
At least in the IMC, the big changes for A2L refrigerants came in the 2021 version. I haven't dealt with any on a project yet, and haven't looked too hard at the 2024 IMC yet. I would say if you are on older versions of the code, you would treat the A2L refrigerants as any other A2 refrigerant, because that's the group they are a subset of. One problem I did notice looking in my 2018 IMC is that none of the R-454s are even listed in the refrigerant charts, so if they are used you may have no choice but to look into newer codes for at least that info. I don't know how else you would address them.
 
The biggest issue for me, as an architect, is the linesets have to be in a dedicated, fire rated, ventilated and monitored shaft. Previously I would provide a 6" wall on two sides of the AHU stacks and call it a day. But now I have to coordinate a rated route with MEP (plus monitoring and ventilating) and take space from the sellable/ leasable area for the shafts, which developers will hate. And of course I won't be paid more for all this extra work.

But at least I learned about this ahead of time. Hopefully others will stumble across this too before it becomes an issue. Learning about this as a permit review comment would be painful. Ooof
 
Depending on the building layout, it may be an option to route the piping to the exterior and then up/down and then cover it with a decorative enclosure that's not fully enclosed. For replacements that may be about the only option. Also you are allowed to go through 2 floor/ceiling assemblies before a rated shaft is required.
 
Resurrecting this thread:

A2L refrigerants will take over the market at the beginning of 2025. You pretty much won't be able to get the 410A systems we use now.

It appears to me that under the 2021 I-Codes, there are no specific requirements triggered in commercial unless a “machinery room” (defined term) is required by the IMC. Machinery rooms are required when you exceed the pound limit of refrigerant allowed for that occupancy (which varies by refrigerant but will never be required under 6.6 pounds). The IMC sections come from chapter 11, and there are some IFC sections in 608. It appears that the amount of A2L that would trigger a machinery room is much lower than the old non-flammable stuff, so we could run into issues in a lot of existing buildings when an A/C unit needs replaced.

The machinery room must have a 1-hour fire rating or sprinklered, can have no open flame or a continuously hot surface over 800 F, must have refrigerant leak detection installed that triggers emergency ventilation that sucks the refrigerant gasses out of the room and dumps them out at least 15’ above grade and 20’ away from any window, opening, or exit. There has to be a break-glass or tamperproof emergency shut-off switch that turns off the refrigerant pumps, compressors, etc., but cannot be used to turn them back on. There are some exceptions for rooms that meet Class 1 Division 2 status in the NEC.

Given all of that, I have two questions:

(1) Do you require the amount of refrigerant that will be in a system to be specified on the plans for new construction in commercial, in order to determine if a machinery room is required?

(2) When replacing an existing A/C with a new A2L unit, do you require in the submittal for them to provide the amount of refrigerant the system will carry so that we know if the existing room is big enough for the new stuff without triggering the "machinery room" requirements?
 
brokenkeys said:
The biggest issue for me, as an architect, is the linesets have to be in a dedicated, fire rated, ventilated and monitored shaft. Previously I would provide a 6" wall on two sides of the AHU stacks and call it a day. But now I have to coordinate a rated route with MEP (plus monitoring and ventilating) and take space from the sellable/ leasable area for the shafts, which developers will hate. And of course I won't be paid more for all this extra work.

But at least I learned about this ahead of time. Hopefully others will stumble across this too before it becomes an issue. Learning about this as a permit review comment would be painful. Ooof
Click to expand...
Everyone is going to try to get a mod to ASHRAE 15 and/ or 34 or whatever it is with a shaft alternative....Or 2027 when they get that approved....

1109.2.5​

Refrigerant piping that penetrates two or more floor/ceiling assemblies shall be enclosed in a fire-resistance-rated shaft enclosure. The fire-resistance-rated shaft enclosure shall comply with Section 713 of the International Building Code.

Exceptions:

  1. 1.Systems using R-718 refrigerant (water).
  2. 2.Piping in a direct system using Group A1 refrigerant where the refrigerant quantity does not exceed the limits of Table 1103.1 for the smallest occupied space through which the piping passes.
  3. 3.Piping located on the exterior of the building where vented to the outdoors.

1729888135178.png
 
Beniah Naylor said:
Resurrecting this thread:

A2L refrigerants will take over the market at the beginning of 2025. You pretty much won't be able to get the 410A systems we use now.

It appears to me that under the 2021 I-Codes, there are no specific requirements triggered in commercial unless a “machinery room” (defined term) is required by the IMC. Machinery rooms are required when you exceed the pound limit of refrigerant allowed for that occupancy (which varies by refrigerant but will never be required under 6.6 pounds). The IMC sections come from chapter 11, and there are some IFC sections in 608. It appears that the amount of A2L that would trigger a machinery room is much lower than the old non-flammable stuff, so we could run into issues in a lot of existing buildings when an A/C unit needs replaced.

The machinery room must have a 1-hour fire rating or sprinklered, can have no open flame or a continuously hot surface over 800 F, must have refrigerant leak detection installed that triggers emergency ventilation that sucks the refrigerant gasses out of the room and dumps them out at least 15’ above grade and 20’ away from any window, opening, or exit. There has to be a break-glass or tamperproof emergency shut-off switch that turns off the refrigerant pumps, compressors, etc., but cannot be used to turn them back on. There are some exceptions for rooms that meet Class 1 Division 2 status in the NEC.

Given all of that, I have two questions:

(1) Do you require the amount of refrigerant that will be in a system to be specified on the plans for new construction in commercial, in order to determine if a machinery room is required?

(2) When replacing an existing A/C with a new A2L unit, do you require in the submittal for them to provide the amount of refrigerant the system will carry so that we know if the existing room is big enough for the new stuff without triggering the "machinery room" requirements?
Click to expand...
The above really should have been a response to you...
 
So, on the plan review side, I have two questions:

(1) Do you require the amount of refrigerant that will be in a system to be specified on the plans for new construction in commercial, in order to determine if a machinery room is required or not?

(2) When replacing an existing A/C with a new A2L unit, do you require in the submittal for them to provide the amount of refrigerant the system will carry so that we know if the existing room is big enough for the new stuff without triggering the "machinery room" requirements?
 
So if you use double wall tubing, can you split up your shaft into multiple sections vertically that are less than 3 stories (compartmentalize) and use 1hr unventilated shafts? Imagine a 1hr horizontal barrier in the 1hr shaft and the ref lines are firestopped.

I have done this before with duct shafts penetrating more than 3 stories by putting a F/S damper horizontally in line with a horizontal 1hr barrier.

Also, why are we jumping through all these hoops for a refrigerant that is far less flammable than natural gas for which we run lines almost wherever we want with no protections?
 
redeyedfly said:
So if you use double wall tubing, can you split up your shaft into multiple sections vertically that are less than 3 stories (compartmentalize) and use 1hr unventilated shafts? Imagine a 1hr horizontal barrier in the 1hr shaft and the ref lines are firestopped.

I have done this before with duct shafts penetrating more than 3 stories by putting a F/S damper horizontally in line with a horizontal 1hr barrier.

Also, why are we jumping through all these hoops for a refrigerant that is far less flammable than natural gas for which we run lines almost wherever we want with no protections?
Click to expand...
Because natural gas is not at high pressure....
 
Thoughts on compartmentalizing shafts?

The A2L change is a pretty big issue for low and mid rise. What are your building departments telling designers?
 
Had a discussion with an ICC representative and determined the following items from our discussion:
  • In existing spaces, it is the intention of the code writers that you are creating a violation when a compliant 410A system is replaced with an A2L system that is too large for the area the original unit was located.

    In other words, the 410A system was legal in a small space, but the A2L system that is the same size may not be. You will either have to make the space bigger, relocate the unit to a compliant location, install multiple smaller units, or construct a “machinery room” with all of the fire separation, refrigerant detection, emergency exhaust, etc.

  • Spaces can be enlarged to gain more cubic feet of volume by adding openings in walls/doors with a grate or a louver, similar to combustion air, as long as that doesn't torpedo a fire rating or something. How to size these openings is another matter entirely, I am not sure how I would do that yet. Probably something to negotiate with the local AHJ.

  • The allowable quantity of refrigerant per 1,000 cubic feet of space varies by refrigerant type, some refrigerants being much better than others. Even the most dangerous refrigerants do not have any requirements for space if the individual systems hold less than 6.6 pounds of refrigerant.

  • The allowable quantity is per unit in the space – the assumption is that only one unit will leak at a time. So, if one unit holds 7 pounds of refrigerant and the other holds 4 pounds, you size the room for 7 pounds. You don’t add the 7 pounds and the 4 pounds together to get 11 pounds.

  • Our department needed to add a few questions to our mechanical permit application to get the poundage and type of refrigerant that will be installed with new or replacement equipment. That is in progress now, when it is ready it will allow us to determine how much of a problem this will be in our area.

  • I spoke to to two local mechanical contractors, they told me that the most common refrigerants they know of at this time are R32 and R454(A, B or C, I’m not sure and they didn’t specify). R-32 allows 4.8 pounds of refrigerant per 1000 cubic feet (a 10x10x10 room), while those in the 454 category allow 22 pounds and up per 1000 cubic feet.
 
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The transfer openings to increase space size would be to adjacent indoor spaces similar to indoor combustion air transfers so you can count the volume of both spaces. But like you said, there's no guidance on sizing those openings.....
 
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