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Foam core PVC pipe use?

Rich Kontny_3
Rich Kontny_3 Member Posts: 562
For plumbing systems it is a poor choice. It tends to crack easier than regular pvc and on tested systems this can be a problem. A co-worker of mine had a weekend emergency and had to use thirty feet of foam core. He found for leaks due to fractured pipe. (not a happy camper)


  • Dale
    Dale Member Posts: 1,317
    Foam core pvc pipe use

    Does anyone know what gas condensing product prohibits the use of foam core pvc besides Munchkin boilers? We had an issue with a Munchkin and read their install instructions which make a big deal of no foam core type pvc for the vent pipe. Several furnace mfgs. say it's acceptable. I'm not a plumber so I didn't know there was a difference, I do now.
  • Good gosh,

    Mark Eatherton, will you take this one?
    In our jurisdiction, it`s still OK for underground building drains, or septic lines, that`s about-it.

  • Cam_2
    Cam_2 Member Posts: 36
    Foam Core

    Non-pressure,DWV applications. Drainage, Waste & Vent. That's all...

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    To the best of my knowledge,,,

    it is approved ONLY for combustion air piping. No manufacturer I'm aware of would allow the use of foam core for the exhaust, unless they WANTED to be put out of business...

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Todd S_14
    Todd S_14 Member Posts: 1
    Plastic Vent Pipe

  • Derheatmeister
    Derheatmeister Member Posts: 1,515

    although it is approved for combustion air it is best not to even have foam core on site so that there is no mix up or confusion!
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    True true...

    And that is EXACTLY why we never carried ANY foam core pipe in our inventory.

    Too easy to slip up and someone could die because of it.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • ToddS
    ToddS Member Posts: 1
    Charlotte Pipe

    Recently addressed the plastic venting issue:

  • Buzz G.
    Buzz G. Member Posts: 61
    foam core pvc

    is NOT OK for Knight Lochinvar either-suspect that none of the manufacturers allow it.
  • EricAune
    EricAune Member Posts: 432
    Temp, Temp and Temp

    Foam Core pipe is not rated for the temperatures that can be introduced in the exhaust system.
    All Schedule 40 plastic is for no-pressure, its not an issue of pressure, its the temperatures
    "If you don't like change, your going to like irrelevance even less"
  • Dale
    Dale Member Posts: 1,317
    Thanks guys

    Thanks for the input, I was surprised to find most of the furnace manufactures allow foam core for inlet or exhaust so be careful if you inspect and want to condemn one. I agree about not having any in the shop, that is now our policy, why risk it. I have found no available test data on the product for heating use, probably because the pipe manufacturers don't want the liability for what is to them a very small part of the plastic pipe business.
  • Don \"Grumpy\" Walsh
    Don \"Grumpy\" Walsh Member Posts: 184
    Why bother?

    In my area the cost difference between 4" foam core and 4" PVC is .48¢ a foot. Why would anyone put their reputation on the line for that little gain?
  • eluv8
    eluv8 Member Posts: 174
    fractured foam core?

    Foam core manufactures and even solid core pvc manufactures will tell you their pipe was not intended to be used as boiler venting. I have never asked about furnaces although its seems popular in the HVAC industry, Nor do they want any liability for doing so. There is debate on wether solid core pvc has a high enough temperature rating let alone foam core. My vote is all boilers have an integral high limit safety linked to the flue sensor, unfortunately that would require the installing contractor to correctly program the control for the venting used, or just another thing for the government to monitor or both.

    15 years I have rarely seen abs crack even in 0 degree weather, more from smashing than anything, PVC or solid core on the other hand I have had crack and shatter especially as the weather gets colder. The only time I used PVC solid core was when I wanted a nice straight looking install that was going to remain visible on Plumbing Drain Waste and Vent. Had several HVAC contractors put in the boiler vent for me through the roof and had several change them out afterwards not happy with me the entire time even when they were specifically instructed to use solid core.
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