A2L Refrigerant Piping installation Chase requirements silent in the building code

[Builder Bob]

Just a quick question - It appears that I can run Natural Gas or propane lines without Chases in a building but if I install A2L refrigerant I have to run it in a rated fire chase according to the Mechanical Code? ICC needs to coordinate the code books together to reflect the requirements of each other - not hide a potential building construction requirement in the Mechanical Code. Second part of rant - I can run propane (LPG lines) up four stories without a chase connected to a 250- or 500-gallon propane tank but If I install a three-ton split unit with A2l on the third floor I have to run these in a rated chase (Unit contains between 6 to 18 lbs. of refrigerant.)

Can somebody explain the knee jerk reaction to this to me??

Sorry had to vent! (no pun intended)

Back to your regularly scheduled Building Forum - Back to you Jeff.....

 

[Builder Bob]

Reference - Sorry forgot to add this
2021 and 2024 IMC Section 1109.2.5

(Rated shaft required if you penetrate more than 2floors....Paraphrased)

 

[steveray]

Is the A2L odorized? That'd be my guess.........But then again...I never did make it as a Carnie....

 

[klarenbeek]

I kind of wondered the same thing with natural gas vs. A2L refrigerant. The refrigerant is a low flammable item but not odorized and under high pressure. That's the only reasons I can think of why it would have to be in a ventilated rated shaft but gas line doesn't