Closed and Open Cell Pipe Insulation - Help me understand

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Ryan Mattox

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Dear experienced Craftsmen:

I have a question about plumbing pipe insulation and code. I am a refrigeration contractor, so in my world, everything is closed cell insulation. However, I observe that plumbers still (primarily) use open cell pipe insulation.

Recently, I sold my house, and I had insulated some hot water piping in the attic with closed cell insulation. The inspectors recommended that all my neat work be replaced with open cell insulation. I was flabbergasted. I did not understand why the inspector wanted me to reduce the R-value of the insulation on the pipes. Therein lies my question.

Why is open cell pipe insulation used in favor of closed cell insulation in the plumbing world? Why would a plumbing inspector fail closed cell insulation and demand that it is replaced with open cell insulation? The only reason I can fathom is that closed cell insulation may carry water in the case of a water leak whereas open cell insulation would allow the leak to drip through the insulation. I can imagine this would make the leak easier to find and repair.

Can you help me understand why the codes are so different here? Thanks in advance for your help.

Humbly,

Ryan
 

SHEPLMBR

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Did you ask the inspector? How high of a temp rating is the closed cell good for?
 

Ryan Mattox

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